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.

Joan bought a total of 9 t-shirts, but also a pair of socks. We don't know the price of the shirts, but they were all the same price, and her total was 79 bucks. If she bought socks for 7 bucks, we subtract 7 from 79, which leaves us with 72. Now we divide 72 with the amount of shirts she bought, which is 9, you get 8. Each shirt was 8 bucks.

Let's do the same thing for Kylie. She bought water balloons for 3 bucks, which if we subtract that from the total amount, we would have 56 bucks left. She bought seven T-Shirts at the same price, which, 56 divided by 7 would leave us with 8 bucks for each shirt.

Step-by-step explanation:

hope this helps!

51

step-by-step explanation:

73-22=51 the   mass number minus the amount of protons gives you the amount of neutrons