Question 918080
r1 =6
r2 =8
t  = ?

[(1/r1) * t] + [(1/r2)*t] = 1

t/6 +  t/8 = 1  

multiply by common denominator... 24

24 (t/6 +  t/8 = 1)

4t + 3t =24

7t = 24

t = 24/7 = 3.4hrs