Question 904086
a=6
b=9
1/a+1/b=1/x
1/6+1/9=1/x
1/6+1/9=1/3.6
1/x=1/3.6
x=3.6 hours working together
check
1/a+1/b=1/x
1/6+1/9=1/x
9/54+6/54=1/x
15/54=1/x
54/15=x
x=3.6 hours working together
ok