Need help on writing a system of equations. I can figure it out without the systems but now sure how to write a systems of equations not knowing how many the box can hold.

Question

Dark chocolates cost $0.25 each and milk chocolates cost $0.15 each. Tom wants twice as many dark as milk chocolates in the box. He only has $10 to spend on the chocolates. write a system of equations.

Answer 1

If there are d dark and m milk,

d = 2m
.25d + .15m = 10.00