Math question
hello,
I'm practising my math for the dlr test.
I've a question and i don't how to solve. I'm sure it will be easy but i don't know how to find it:
Person A and B are working together for a task and it takes 48' if they work togethr.
Person A and C are doing the same task and it takes 80 min.
Person B and C are doing the same task and it takes 60 min.
How long are A B C working?
(answer is 48min, 80min, 60min)
Can somebody tell me what calculations you have to make?
thx