Answer:
A. Your friend did not factor the variable from the second term.
Explanation:
15x - 20xy
Your friend was correct in factoring out 5x. However, when you factor out a component from an expression, you have to change each component in the expression.
This means that factoring out 5x will result in: 5x(3 - 4y).
Therefore, your answer is:
A. Your friend did not factor the variable from the second term.
Hope this helps!