If Billy and Ahmad work together, they can complete a job in 12 days. If Billy and Ahmad worked together for 6 days, followed by Ahmad who worked alone for the next 15 days, they can finish off the job.
- How many days would Ahmad need to complete the job alone?
- How many days would Billy need to complete the job alone?
(a)
Time taken by Billy and Ahmad if they work together:
12 days → 1 job
1 day →
112 job
6 days →
612 =
12 job
Time taken by Ahmad if he works alone:
15 days → 1 -
12 =
12 job
1 day →
12 ÷ 15 =
12 x
115 =
130 job
1 job → 30 days
(b)
Time taken by Billy if he works alone:
1 day →
112 -
130 =
360 =
120 job
120 job → 1 day
1 job → 1 ÷
120 = 20 days
Answer(s): (a) 30; (b) 20