Question

How do you solve d + q = 31 and 10d + 25q=5.95?

Answer 1

`d=51.27`
`q=-20.27`

Explanation:

First, notice that `10d+25q=(10d+10q)+15q`

and that `(10d+10q)=10(d+q)=10*31=310`

You will conclude that:
`310+15q=5.95 rarr 15q=5.95-310 rarr q=(5.95-310)/15=-20.27`

From here, you can easily conclude that:
`d+(-20.27)=31 rarr d=31+20.27=51.27`