If one bottle of the national brand of cough medicine costs $12, what is the cost of a bottle of the store brand if its 2/3 of the national brand

Paco orders an ice cream for $1, but realizes his wallet is at home and he only has 3/20 of $1 with him. if his mom pays the remaining 7/20 of the dollar, how much will she pay? $0.05 $0.15 $0.85 $0.95