Kayla and Riley both solved the equation x-15 = 13-7, using substitution. Kayla says the answer is x=21, and Riley says that answer is x=28. Which student is correct?

Answer 1

To solve the equation x-15 = 13-7 using substitution, we need to substitute the values of x and see if both sides of the equation are equal.

Case 1: Kayla's answer x=21
Substituting x=21, we get:
21-15 = 13-7
6 = 6
Both sides are equal, so Kayla is correct.

Case 2: Riley's answer x=28
Substituting x=28, we get:
28-15 = 13-7
13 = 6
Both sides are not equal, so Riley is incorrect.

Therefore, Kayla is the correct student.