Help me please!! use image as well

What can you determine about the solutions of this system

If johnny ate 5 cans of sugar, but in the kitchen they only had 3. what did johnny eat? (he found a secret stash btw.)

Astore is having a sale in which all items are reduced by 20 percent. including tax, jennifer paid $21 for a pair of shorts. if the sales tax is 5 percent, what was the original price of the shorts