peter has 3 different kinds of buttons in one box. there are 124 more ivory buttons than plastic buttons and 1/3 as many wooden buttons as ivory buttons. there are 72 wooden buttons. how many plastic buttons are there?
x plastic buttons
(x + 124) ivory
1/3(x + 124) wooden
1/3(x + 124) = 72
Multiply both sides by 3:
x + 124 = 72
x = 92 plastic buttons