Since 3 1/6 is only 1/3 of what he is watering, you can multiply the 3 1/6 by 3 to find your answer
9 1/2 should be your answer.
First you multiply the whole number by 3
3x3 = 9
Now we multiply the fraction
1/6 x 3 = 1/2 because we multiply the 1 on top. 3x1 = 3 and 3/6 is reduces to 1/2