Griffin and Marco have 342 coins altogether. Griffin's coins is equal to 4/5 of Marco's coins. How many more coins does Marco have than Griffin?
Let the number of Marco's coins==M
Then Griffin's number of coins==4/5M
M + 4/5M ==342, solve for M
9/5M == 342
9M == 342 * 5==1,710
M==1,710 / 9==190 coins - Marco's share
342 - 190 ==152 coins - Griffin's share
190 - 152 ==38 extra coins that Marco has.
Check: 152 / 190 ==4 / 5