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Comparing with multiplication and addition: giraffe

CCSS.Math:

Video transcript

we're told that Imran is two years older than dia dia is - how old is Imran so I encourage you to pause this video and try to think about this yourself how old is Imran given the information here so let's use some letters to represent Imran and Diaz age let's say that I is equal to M Ron's age M Ron's age and let's say that D is equal to D as age D is equal to D is d is age so given that what is this first sentence tell us it says that in Ron's age Imran is two years older than via so Imran Imran sage is going to be equal to D as age is going to be equal to D is age plus two plus two that's what this first sentence tells us in Ron's age is d is age plus two in Ron is two years older than diya another way you could think about it if we were to imagine their ages on a number line right over here so if this is 0 and then this is D as age right over here this is D as age let me do it in that same color this is D as age right over here if you were to add 2 to D as age so if you were to go to more if you were to go to more so plus 2 you would get 2 in Ron's age you would get to M runs age so that's what this first sentence tells us then they tell us that dia is 2 so that's like saying that D which we're using to represent D as age that's going to be equal to 2 so this thing is equal to 2 this thing right over here is equal to 2 so we can rewrite this as M Ron's age is equal to D as age which we now to be know to be 2 + 2 + 2 so what's 2 plus 2 well you know that that's going to be 4 so in Ron's age is going to be equal to 4 if this is 2 right over here and then you were to go up 2 more you're going to get to 4 in Ron's age is 4 let's try one more of these so here we're told that the giraffe at the zoo is three times taller than Shan thenew Shan 'then who is six feet tall how tall is the giraffe so once again I encourage you to pause this video and try to think about it on your own well soon as this do the same idea let's use some letters to represent the different the different heights so G for giraffe and s for Shantanu so they say the giraffe the and I'll use G for the height of the giraffe the height of the giraffe is three times taller is three times taller not three more feet three times taller then Sean thenews height so we could say that the giraffes height is equal to three times three times Shan thenews height three times Shan thenew sides so just let's be clear with it the G represents the height of the giraffe s represents the height of Shantanu so another way of thinking about it let me see if I can draw giraffe reasonably here so if this is the giraffe actually s isn't a bad job at drawing a giraffe so this is the giraffe right over here they're saying that if you take shot lose height times three you get to the giraffes height so let me make actually giraffe might have longer legs than that so this is G the height of the giraffe is G and Sean thenews height so let's say this is Sean to decide if I multiply that by three I get the giraffes height so let me divide let me see one - so Sean thenew might look something like this and if you took three times his height so this is one time his height two times his height three times his height you would get to the height of the giraffe so that's what this first sentence tells us Sean thenew is six feet tall so they tell us that this height right over here this height right over here is six feet or another way of saying it is s is equal to six feet how tall is the giraffe well once again s is equal to six feet so the giraffes height is equal to 3 times Sean thenews height which we now know to be six feet so three times 6 feet so in feet the giraffe's height is 3 times 6 well we know that 3 times 6 is 18 giraffes height is and we're dealing with feet so the giraffes height is 18 feet and you see that right over here 6 feet plus another 6 feet plus another 6 feet or 6 feet times 3 is going to get you is going to get you to 18 feet