Question

What common error(s) did this student make? What is the correct solution for x? Please help

Answer 1

x = 3

Explanation:

The first error was in the 2nd line: -5(x - 1) is -5x + 5, not -5x - 5 = 20.

Continuing the solution:

10x - 5x + 5 = 20

Combining like terms, we get

5x = 15, and so x = 3

Answer 2

10x - 5(x - 1) = 20

10x - 5x + 5 = 20

5x + 5 = 20

5x = 20 - 5

5x = 15

x = 15/5

x = 3

Explanation: