text: Let Q = the number of quarters Quincy has.  They are worth 25Q cents.\n\nDirk has (Q+5) dimes worth 10(Q+5) cents = 10Q + 50 cents\n\nWhen Natalie gives Dirk a nickel he now has 10Q + 55 cents, but he then gives a dime to Quincy leaving Dirk with 10Q + 45 cents and Quincy with 25Q + 10 cents.\n\nFinally Quincy gives away a quarter leaving him with 25Q - 15 cents, which equals Dirk's money or 10Q + 45\n\n25Q - 15 = 10Q + 45\n\nSubtract 10Q from both sides: 15Q - 15 = 45\n\nYou can finish from here I am sure.