Question

A student has 40 dimes and nickels. Their total value is $3.25. If d = number of dimes and n = number of nickels, this system of equations represents the situation:

Answer 1

Solution

Solving the two-equation simultaneously,

$\begin{gathered} d+n=40\equiv10d+10n=400\text{ --------\lparen1\rparen} \\ \\ 0.10d+0.05n=3.25\equiv10d+5n=325\text{ ------\lparen2\rparen} \\ \\ (1)-(2) \\ \\ (10-5)n=400-325 \\ \\ 5n=75 \\ \\ n=15 \end{gathered}$

When n = 15

$\begin{gathered} d=40-n \\ \\ d=40-15=25 \end{gathered}$

The correct option is C