2012 AMC 12B Problems/Problem 3
For a science project, Sammy observed a chipmunk and squirrel stashing acorns in holes. The chipmunk hid 3 acorns in each of the holes it dug. The squirrel hid 4 acorns in each of the holes it dug. They each hid the same number of acorns, although the squirrel needed 4 fewer holes. How many acorns did the chipmunk hide?
If x is the number of holes that the chipmunk dug then, 3x=4*(x-4). so 3x=4x-16. x=16, and to find number of acorns hid by chipmunk, multiply by three, to get 48; D.