Louis has three more quaters than dimes in his pocket, for a total of $1.80. Which equation could used to detemine the number of dimes, x in this pocket

3+d=q and 0.10d+0.25q=1.80

There are 3 dimes and 6 quarters.

Step-by-step explanation:

This situation has two unknowns - the total number of dimes and the total number of quarters. Because we have two unknowns, we will write a system of equations with two equations using the two unknowns.

We know there are three more quarters than dimes. We write that as 3+d=q.

We also know the total cost and the value of each coin. We write 0.10d+0.25q=1.80.

We substitute 3+d for q in the second equation.

0.10d+0.25 (3+d) = 1.80

0.10d+0.75+0.25d=1.80

0.35d+0.75=1.80

We isolate the variable by subtracting 0.75 across the equal sign and then dividing by the coefficient of d.

0.35d=1.05

d=3

There are 3 dimes.