Question

two mechanics, martin and gordon, are working on your car. martin can complete the work in 4 hours, while gordon can complete the work in 2 hours. how many hours does the maintenance take if they work together? a.one half b.three fourths c.six eighths d.four thirds

Answer 1

Let x be the time in hours it takes for Martin and Gordon to finish the job if they work together. Within this time, Martin and Gordon do x/4 and x/2 work individually, respectively. The sum of the two works should be equal to 1. 
                                       x/4 + x/2 = 1
The value of x is 1 1/3. Thus, the answer is letter D. 4/3 hours.