Don has 3 more than twice as many quarters as Greg. If they have 18 quarters altogether, how many quarters does Don have?

Let us assume that the number of quarters Greg has = x

Then the number of quarters Don has = 2x + 3

Together they have 18 quarters

then

x + 2x + 3 = 18

3x = 18 - 3

= 15

x = 5

So the number of quarters Greg has is 5

Then the number of quarters Don has = 2x + 3

= (2 * 5) + 3

= 10 + 3

= 13

So it can be concluded that Don has 13 quarters.