Question

An apple has 24 fewer calories than a banana. If 7 bananas have the same number of calories as 10 apples, how many calories are in a banana

Answer 1

if apple is x and banana is y
y-24=x
7y=10x=>7(x-24)=10x=>10x-7x=168=>3x=168=>x=56 so y=80 so banana's calories is 80

Answer 2

Substitute for "a" and solve for "b":
7b = 10(b-24)
7b = 10b-240
3b = 240
b = 80 (# of calories in a banana)