The answer you are looking for is 40 hours. they gave you the answer in the statement above when they said he gets time-and-a-half for any hours beyond 40. So he only worked 40 regular pay hours and got 4 hours overtime for time-and-a-half.
Answer:
35.4m below sea level
Step-by-step explanation:
172.5 - 137.1 = 35.4
Mixture problem.
Ratio of 20% : 50% acids
=50-39 : 39-20
=11:19
total volume
=400L
vol. of 20% acid=400*(11/(11+19)=400*(11/30)=146.667 L
vol. of 50% acid=400*(19/(11+19)=253.333 L
Alternatively, use c=volume of 20%, d=vol of 50%
then
0.2c+0.5d=400*0.39
Since c+d=400, we have
0.2c+0.5(400-c)=400*0.39=156
solve for c:
0.3c=44
c=146.667 and d=400-c=253.333 as before.