Now translate each sentence into an equation:
" you volunteer a total of 40 hours" s+ p+ c= 40.
"You spend 4 times as many hours collecting toys as picking up trash"
"You spend 2 hours less serving at the soup kitchen than picking up trash"
s= p- 2.
So your three equations can be written
s+ p+ c= 40
-4p+ c= 0
s- p= -2
Now, Cramer's rule says that the solution can be written s= u/d, p= v/d, and c= w/d where d is the determinant formed from the coefficients and u, v, w are the same determinant but with the first, second, and third columns, respectively, replaced by the numbers on the right hand side of the equations.
Can you find those determinants by yourself?