AMC 10 2015a

What is the value of $(2^0-1+5^2+0)^{-1}\times 5$ ? $\textbf{(A) }-125 \textbf{(B) }-120 \textbf{(C) }\dfrac15 \textbf{(D) }\dfrac5{24} \textbf{(E) }25$

A box contains a collection of triangular and square tiles. There are 25 tiles in the box, containing 84 edges total. How many square tiles are there in the box? $\textbf{(A) }3 \textbf{(B) }5 \textbf{(C) }7 \textbf{(D) }9 \textbf{(E) }\text{11}$