Can someone teach me about percent increases and decreases with equations?

Asalesperson earns $320 per week plus 8% of her weekly sales. the expression representing her earnings is 320 + 0.08x. which of the following describes the sales necessary for the salesperson to earn at least $1000 in the one week?

1yd 1 ft = 1 1/12 1 1/3 1 1/2 1 1/6

Due to financial difficulties the owner of 4 skateboard stores is going to close 2 of his stores. based on the money earned at each store, which two stores should remain open?