Question

A and B can do a work in 10 days and 15 days respectively. A starts on the work and both work alternately days
after days in how many day will the work be completed ?
please give correct answer please ​

Answer 1

A 1 day work = 1/10
B 1 day work is 1/15
A+b 2 day work is 1/6
1/1/6 is 6
6 x2 is 12 days
So answer should be 12 days