The admission fee to a museum is $12.50 per nonsenior adult, $8 per child, and $6.50 per senior citizen. A tour group consists of m nonsenior adults, $\left(\frac{5}{4}m+6\right)$ children, and 8n senior citizens.
(a) What is the total admission fee of the group?

(b) Write an expression for the admission fees of the children in the group subtracted from the combined admission fees of the nonsenior adults and senior citizens in the group.

(c) Evaluate your expression from b), when m = 24 and n = 4.