+56 You have some marbles. You are left with 6 marbles if you give each of your friends 11 marbles. You will need 12 more marbles if you give 14 marbles to each of your friends. How many friends do you give the marbles to? How many marbles do you have?
+318 Set the number of friend is x, the number of marbles is y.
everyone 11 marbles, left 6 marbles
So 11x + 6 = y (1)
everyone 14 marbles, red 12 marbles
So 14x - 12 = y (2)
according to (1), (2)
11x + 6 = y => x = 6
14x - 12 = y y = 72
So there are 6 friends, 72 marbles.
