Your piggy bank has a total of 46 coins in it; some are dimes and some are quarters. If you have a total of $7.00, how many quarters and how many dimes do you have?

Question

anonymous · Answer

This kind of problem is very common in algebra. Because there are 2 variables (dimes and quarters), you need to come up with 2 equations to solve it. (Unless you did guess-and-check).
You have 2 things going on here: the number of the coins and the value of the coins. So one of your equations will be about the number, and the other will be about the value. 
Can you write those two equations? (Use d for number of dimes and q for number of quarters)