Mike, Ron, Debra, and Susie divided a $47 refund so that Mike and Ron together got $27, Mike and Debra got $25, and Mike and Susie got $23. How much did Debra get?
Mike got $14.
Ron got $13.
Debra got $11.
Susie got $9.
One way to get it: M + R + D + S = $47.
But M + R = 27,
M + D = 25, and
M + S = 23.
Substituting R, D, and S in terms of M and simplifying, 2M = 28, so M = 14, and it's easy from here.
For students who do not have a grip on algebra, here is a nice question that can lead to the solution without using algebra: Notice that 27 + 25 + 23 = 75, which is not 47 — why not? Someone will notice that Mike's share has been included 3 times, so 75 - 47 = 28 must equal the 2 extra Mike shares. The solution follows easily.