*machine x can produce 1,200 bolts in 4 hours and machine y can produce 1,000 bolts in 5 hours. working together at these constant rates, how long will it take it them to produce 1,000 bolts
This is the concept of proportionality.To solve the expression we proceed as follows; Machine X; Proportion of work completed in 1 hour will be: 1/1200
Machine Y; Proportion of work completed in 1 hour will be:
1/1000
Proportion of work completed by both machines in 1 hour will be: 1/2000+1/1000 =3/2000 number of bolts produced by both machines in 1 hour will be: 666 2/3 bolts; Time taken to produce 1000 bolts will be: 1000/[666 2/3] =1 1/2 hours