Question

A bag is filled with green and blue marbles. There are 105 marbles in the bag. If there are 9 more green marbles than blue marbles, find the number of green marbles and the number of blue marbles in the bag.

Answer 1

for the blue, just solve
b + b+9 = 105
and then you can get the green

Answer 2

or, as a more Gauss-like method, assume they are half-and-half
(or almost, since there is an odd number)
52+53 = 105
now, since the amounts are separated by 9, rather than 1, just move away 4 in each direction
48+57 = 105

Answer 3

Thanks:)