Add or subtract numbers from both sides
we are given in the problem the number of hours Peter has played for video games. In this case, f(x) is the number of hours of playing with x as the number of weeks of playing. In this case, the equation f(x) = 5x.
Simplify
4ax+12-3ax=25+3a
ax+12=25+3a
ax-3a=25-12
a(x-3)=13