Question 270270
Add their rates of digging to get 
the rate of them digging together
Ryan's rate:
(1 hole/5 hrs)
Castel's rate:
(1 hole /6 hrs)
I want to add their rates to find
(1 hole)/(x hrs)
{{{1/5 + 1/6 = 1/x}}}
Multiply both sides by {{{30x}}}
{{{6x + 5x = 30}}}
{{{11x = 30}}}
{{{x = 30/11}}}
It will take them about 2.73 hrs 
to dig the hole working together