Joan and Kylie are shopping at the mall. Joan buys a pack of socks for $7. She also buys nine T-shirts, each marked at the same price. She spends a total of $79. Kylie buys a pack of water balloons for $3. She also buys seven T-shirts, each marked at the same price. Kylie spends a total of $59. The equation 9x+= can be used to represent Joan’s purchases. The equation x+= can be used to represent Kylie’s purchases.