I don't know how to make an equation for this?

Vanilla cookies $5/ box
Chocolate cookies $3/box
Mint cookies $2/box

Mary was selling girl guide cookies. She sold twice as many vanilla cookies as she did chocolate cookies. She sold 75 more boxes of mint cookies as she did chocolate cookies. The total sale of the cookies is $675. How many boxes of each type of cookie did she sell?

2 answers

it's a system of equations

5 V + 3 C + 2 M = 675

V = 2 C

M = C + 75

substitute and solve
Thanks!