A bag contains green marbles and red marbles, 83 in total. The number of green marbles is 7 less than 4 times the number of red marbles. How many green marbles are there?

Answer 1

g + r = 83

g = 4r - 7

Substitute:

4r - 7 + r = 83

5r = 90

r = 18

g = 65