4y=40

y = 40 \4

y= 10

A: Each hamburger 10 yuan.

Note: Because Aunt Li gave it to 50 yuan, she got back 10 yuan. It means that 50 yuan lost 10 yuan, so we use 50- 10 to figure out how much four hamburgers cost. Then use 40÷4, because how much per hamburger is a factor, and the factor is calculated by the product ÷ another factor = factor. Because each hamburger has been set to Y, 4y is the total price * * *, and because "=" in the equation is the corresponding number, the total price of four hamburgers is also calculated by 50- 10.

Hope to adopt. . . . . . . . . . . . . . . . .