What we know is that A + S = 111. That is, the miles Andre drove plus the miles Scott drove totalled 111 miles. What we also know is that Scott drove quite a bit more than Andre did. Scott drove 7 miles more that ( +7 ) 3 times the number of miles Andrea drove. That looks like this algebraically:
S = 3A + 7
Now we can sub in that value for S to the original equation:
