Marcos and Oliver have 324 markers altogether. The number of markers Marcos has is equal to 80% of Oliver's markers. How many more markers does Oliver have than Marcos?
Let Oliver's markers = N
Then Marcos's markers = .80N
So
N + .80N = 324 simplify
1.80N = 324 divide both sides by 1.80
N = 324 / 1.80 = 180 = Oliver's markers
.80 ( 180) = 144 = Marcos's markers
Oliver has 180 - 144 = 36 more
+313 
