Question

A bag contains purple marbles and green marbles, 71 in total. The number of purple
marbles is 9 less than 4 times the number of green marbles. How many purple
marbles are there?

Answer 1

Answer:

$55 \: purple \: marbles$

Step-by-step explanation:

$Let \: x, y \: be \: the \: number \: of \: purple \: and \: green \: marbles \: respectively \\ We \: have \: a \: system \: of \: equation: \\ \begin{cases}x + y = 71 \\ x + 9 = 4y \end{cases}\Leftrightarrow \begin{cases}x = 55\\ y = 16 \end{cases}$