18+2.50=20.50 so tax is 10% so you can put that into a calculator as 20.50*0.10 which equals 2.05 so just add 20.50 and 2.05 which is 22.55 is your final answer
B this answer is 4 it’s correct
P(A) = P(8) + P(9) + P(10) = 3/10 so P(A complement) = 1 - P(A) = 1 - 3/10 = 7/10 - D
12 * 20% = 12 * 0.20 = 2.4 hours
It will not last his entire shift.