7+3+8+3=21 fishes in total
8/21 fishes are healthy
8/21 = 0.4 => 40%
Ted rented the bike for 8 hours
cost of Bike $10
50-10=40
40/5, (because each hour costs $5)=8
N equals to 2 so 4 plus 2 is 6 and that is the answer!!
Glad I could help. Have A Good day