I don't understand how to get equation for this

Annie was selling girl guide cookies she sold twice as many vanilla cookies as she did chocolate. She sold 75 more boxes of mint cookies than she did chocolate. Total sale of cookies = 675 how many boxes of each type of cookie did she sell?

Vanilla = 5 dollars per box
Chocolate = 3 dollars per box
Mint = 2 dollars per box

2 answers

M=C+75
V=2C

5V+3C+2M=675
5*2c+3c+2(C+75)=675
10C+3C+2C=675-150
15C=525
C=35 boxes
V=70 boxes
M=110 boxes
check that
Thank you so much !!