4/5 + 1/10 + 5/6 
One thing you can do is make the denominator equal. 
4/5(2/2) + 1/10 = 8/10+1/10 = 9/10 
9/10 +5/6 
Or you could cross multiply, by multiplying the denominator with the opposite numerator (this is the numerator) then multiply the denominator ( this is the denominator) 
(6(9)+5(10))/6(10) = 104/60 then simplify to 26/15