Question

Henry showed all the steps he took to solve the equation.

4 (negative one-half x + 7) + 5 x = 15

Step
Simplified Expression
1
-Negative 2 x + 28 + 5 x = 15
2
3 x + 28 = 15
3
3 x = 15
4
x = 5

Sammy tried to verify the solution by substituting x = 5 back into the original equation. It did not result in a true statement. Which explains why Henry’s solution is incorrect?
Step 1 is wrong because the distributive property of equality was used incorrectly.
Step 2 is wrong because the addition property of equality was used incorrectly.
Step 3 is wrong because the subtraction property of equality was used incorrectly.
Step 4 is wrong because the division property was used incorrectly.

Answer 1

Step 3 is wrong because the subtraction property of equality was used incorrectly.

From Step 2: 3x + 28 = 15. Subtract 28 from both sides: 3x = 15 − 28 = −13. Then x = −13/3, which does check in the original equation. Henry incorrectly left 3x = 15.