Leon has some éclairs. If he gave his friends 8 éclairs each, he
would be short of 12 éclairs. If he gave his friends 4 éclairs each, he
would have 4 éclairs left. How many éclairs would Leon need if he
gave his friends 6 éclairs each instead?
if he has x friends, then
8x-12 = 4x+4
x = 4
6x = 24 eclairs for 4 friends
so he must have 20 eclairs, since 8*4 = 32 = 20+12
4*4 = 16 = 20 -4