A1. If $\frac{5}{6}$ of a number is equal to 25, then $\frac{6}{5}$ of the same number is equal to:
(A) 3.5
(B) 11
(C) 30
(D) 36
(E) 49
A1. Let the unknown number be denoted by $x$ and write the relationship $\frac{5}{6} \cdot x=25$, from which we get $x=30$. We also use the relationship $\frac{6}{5} \cdot x=y$. We calculate $y=36$.