Mikayla and Jesse both solved the equation x−15=12−8, using substitution. Mikayla says the answer is x=19, and Jesse says the answer is x=27. Which student is correct, and how do you know? Show your work and explain your thinking.

Answer 1

To solve x−15=12−8 using substitution, we need to replace the expression 12−8 with its value, which is 4.

Mikayla substituted 4 for 12−8 correctly and solved the equation as follows:

x−15=4
x=19

Therefore, Mikayla is correct.

Jesse substituted 4 for 12−8 correctly, but made an error in solving the equation:

x−15=4
x=27

Therefore, Jesse is incorrect.

We know this because we can substitute each answer back into the original equation and see which one makes it true:

For Mikayla's answer:

x−15=12−8
19−15=12−8
4=4

The equation is true, so Mikayla's answer is correct.

For Jesse's answer:

x−15=12−8
27−15=12−8
12=4

The equation is false, so Jesse's answer is incorrect.

In conclusion, Mikayla is correct and Jesse is incorrect.