Comparing with multiplication and addition: giraffe

We're told that Imran is two years older than Diya. Diya is 2. 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 Diya's age. Let's say that I is equal to Imran's age. And let's say that D is equal to Diya's age. So given that, what does this first sentence tell us? It says that Imran's age, Imran is two years older than Diya. So Imran's age is going to be equal to Diya's age plus 2. That's what this first sentence tells us. Imran's age is Diya's age plus 2. Imran 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 Diya's age right over here-- let me do it in that same color. This is Diya's age right over here. If you were to add 2 to Diya's age, if you were to go to more, so plus 2, you would get to Imran's age. So that's what this first sentence tells us. Then they tell us that Diya is 2. So that's like saying that D, which we're using to represent Diya's age, that's going to be equal to 2. So this thing is equal to 2. So we can rewrite this as Imran's age is equal to Diya's age, which we know to be 2 plus 2. So what's 2 plus 2? Well, you know that. That's going to be 4. So Imran'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. Imran's age is 4. Let's try one more of these. So here we're told that the giraffe at the zoo is 3 times taller than Shantanu. Shantanu is 6 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, let's do the same idea. Let's use some letters to represent the different heights, so G for giraffe and S for Shantanu. I'll use G for the height of the giraffe. The height of the giraffe is 3 times taller-- not 3 more feet-- 3 times taller than Shantanu's height. So we could say that the giraffe's height is equal to 3 times Shantanu's height. So let's be clear. 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 a giraffe reasonably here. So if this is the giraffe-- actually, this isn't a bad job at drawing a giraffe. So this is the giraffe right over here. They're saying that if you take Shantanu's height times 3, you get to the giraffe's height. Actually, a giraffe might have longer legs than that. So this is G. The height of the giraffe is G. So let's say this is Shantanu's height. If I multiply that by 3, I get the giraffe's height. Let me see-- one, two. So Shantanu might look something like this. And if you took 3 times his height, so this is 1 time his height, 2 times his height, 3 times his height, you would get to the height of the giraffe. So that's what this first sentence tells us. Shantanu is 6 feet tall. So they tell us that this height right over here is 6 feet. Or another way of saying it is S is equal to 6 feet. How tall is the giraffe? Well, once again, S is equal to 6 feet. So the giraffe's height is equal to 3 times Shantanu's height, which we now know to be 6 feet, so 3 times 6 feet. So in feet, the giraffe's height is 3 times 6. Well, we know that 3 times 6 is 18. And we're dealing with feet. So the giraffe's 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 to 18 feet.