Explanation:
Let the number of marbles Rowan has = x
Two times x = 2x
3 more than two times the number of marbles Rowan has = 2x + 3
Quinn = 2x + 3
Together they have = 77 marbles
Rowan marbles + Quinn marbles = 77
x + (2x + 3) = 77
x + 2x + 3 = 77
Collect like terms:
3x = 77-3
3x = 74
Divide through by 3:
x = 74/3
x = 24.7
