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### Course: Grade 7 (VA SOL)>Unit 5

Lesson 7: Equations of proportional relationships

# Writing proportional equations from tables

Writing an equation to describe the relationship between the number of scoops in an ice cream cone and the price. Created by Sal Khan.

## Want to join the conversation?

• when x = 1 he wrote 7/4, then when x=2 he wrote 14/4, how is this the same?
• One thing he forgets to make clear in this video, even though the constant is 7/4, is to remember each line is going up by one multiplier (in the left column).

so its 1 x 7/4 and then the next row is 2 x 7/4 (14/4) and then 3x 7/4 (21/4) he explains it as if each value in the last column is 7/4 which is not true. The constant of each row is 7/4. His wording is a bit off that's why it doesn't make sense 100% to everyone.

He says it like each value in the right column is equivalent to 7/4 which is not true at all (we can clearly see that 28/4 is not equal to 7/4 it is 4 times greater). He means the constant of that row is 7/4, but just forgot to word it like that.
• Why did Sal sound so depressed when he said: "I scream. you scream. we all scream for ice cream!"?
• haha idk,he didn't sound that way to me at first, but now i hear it...
• How does he make it look so easy and I am over here still struggling 😭
• he makes it look so simple im still confused
(1 vote)
• since change x/ change y=slope, then if the line doesn't intersect zero then what r u supposed to do?
• If it doesn't intersect zero, then it's not a proportional relationship.
• Does the bigger number always goes on top or can it go on the bottom?
• Big numbers don't always go on top. They can also go on the bottom. Just remember that y always go on top and x goes on the bottom. No matter how big or small a number is, this rule still applies. Most of the time, the small numbers go on the bottom.
• I scream out of pure frustration and anger
• me too
• So when I went to the practice: writing proportional equations, it said "A unicorn daycare center requires there to be 2 supervisors for every 18 unicorns. Write an equation that shows the relationship between the number of supervisors (n) and the number of unicorns (u). I put n=9u because n= 1 supervisor and 9u= 9 unicorns. It said i was wrong so i looked through the hints to see where i messed up and it says the answer is u=9n which means it takes 9 supervisors to care for 1 unicorn. My question is whether I misunderstood the work, or if the answer itself is wrong.
• The hint answer is right because it says that the number of unicorns(u) is equal to 9 times the numbers of supervisors(n), so the equation is indeed u=9n. That is because when it is 1 supervisor(n) the number of unicorns is 9 * 1(9n) in this case 1 which is 9 unicorns, and if the number of supervisors is 2 the number of unicorns is 9 * 2(9n) so the result of 9n will always be the number of unicorns.
• How do you know when the answer to the problem is in fraction form