Gillian can spend up to $300 buying both cotton shirts and wool shirts for her club. the cotton shirts cost $15 each and the wool shirts cost $20 each. the number of wool shirts gillian will buy will be at least 3, but less than half the number of cotton shirts she buys.

which combinations of cotton and wool shirts can gillian buy?

choose all answers that are correct.
a: 13 cotton shirts and 4 wool shirts
b: 9 cotton shirts and 6 wool shirts
c: 15 cotton shirts and 5 wool shirts
d: 10 cotton shirts and 4 wool shirts