Cole goes to the farmers' market every month to buy some of Ms. Lin's homemade jam. The jam costs $5 per jar. Last weekend, Ms. Lin gave a 20% discount for buying at least two flavors. So, Cole bought b jars of blackberry jam and s jars of strawberry jam.
Pick all the expressions that represent how much Cole spent on jam last weekend.

0.20b + 0.20s
0.80 (5b + 5s)
4b + 4s
4 (b + s)

Please include an understandable explanation