Question 129412
Let's call Amanda's age right now, A. 
{{{A+13=2(A-7)}}}
{{{A+13=2A-14}}}
{{{-A=-27}}}
{{{A=27}}}
Check your answer. 
13 years from now, Amanda will be 40.
7 years ago, Amanda was 20.
The original statement is verified.
Amanda is 27 years old.