Question

A can do a piece of work in 20 days, while B can do it in
30 days. If both of them worked together, in how many
days will they be able to finish the work?
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Answer 1

Answer:

12 days is the answer

Step-by-step explanation:

A completes the work in 30 days so he must be doing 1/30th of work per day

similarly

B completes the same work in 20 days so he must be doing 1/20th of work per day

the question is in how many days will they complete their work so we need to firstly know hum much work they do together in a day

so we add up they per day working capacity i.e 1/30 + 1/20 the answer to which you can find out by cross multiplying

[(1)(20)+(1)(30)]/(20)(30)

which equals to 50/600

which turns out to be 1/12

so when both of them work together they do 1/12th of the work per day

so the total number of days they would take to do the entire work together would be 12 days i.e 1/12th of work for 12 days