Answer:
<u>Joe made a mistake in justifying the second and third step</u>.
Step-by-step explanation:
Joe's steps and justifications:
3 + <u>x</u> = 10 Given equation
2
<u>x</u> = 7 Multiplication property of equality
2
x = 14 Subtraction property of equality
Joe made a mistake in justifying the second and third step.
<u>By fixing his mistake:</u>
3 + <u>x</u> = 10 Given equation
2
<u>x</u> = 7 Subtraction property of equality
2
x = 14 Multiplication property of equality