Question 903957
rate for A alone 10
rate for A & B together 6
1/a+1/b=1/x
1/10+1/b=1/6
1/b=1/6-1/10
1/b=10/60-6/60
1/b=4/60
1/b=1/15
b=15
rate for B alone 15
check
1/10+1/15=1/6
15/150+10/150=1/6
25/150=1/6
ok