You can make a system of linear equations, and then solve for x and y.
\({x-y=13}\)
\({x+y=25} \)
Next you can add these two equations together.
\({2x=38}\)
\({x=19} \)
Substituting in our first equation will then give us \({y=6}\)
Multiplying 19 and 6 together gives us 144
