if you substitute this into the other equation that you are given it looks like this 8(326-S)+5S=1972. After this we use PEMDAS to solve for S 2608-8S+5S=1972 2608-3S=1972 -3S=(-636) -S=(-212) S=212 If we know S=212 we can go back and solve the origonal equation for A. A+212=326 A=114