Answer:
4.3 lbs
Step-by-step explanation:
3 1/2 + 4/5 = 3 5/10 + 8/10 = 3 13/10 = 4 3/10 lbs
or
3.5 + 0.8 = 4.3 lbs
I think you have the right one.
Remark
The equation is job1/ time + job2/time = job3/time
Discussion
job one is the time it takes one of the workers to complete the job.
job two is the time it takes the other workers to complete the job
job three is the time it takes to do the job together.
Givens.
Let Marcus's time = m
Let Tony's time be =t
Let their together time = t1
Equation Substitution and solution.
1/m + 1/t = 1/t1
1/6 + 1/4 = 1/t1 The common denominator on the left is 12.
2/12 + 3/12 = 1 / t1
5/12 = 1/t1 Cross multiply.
5*t1 = 12 Divide by 5
t1 = 12/5
t1 = 2 2/5
t1 = 2.4 hours
Cost
1 hour = 43 dollars for labor.
2.4 hours = x dollars for labor.
1*x = 43 * 2.4
x = 103.2 dollars. <<<<< Answer