To solve this equation, we need to combine the like terms on the left side of the equation:

1/3x + 5/3x = 20

To combine the fractions, we need to find a common denominator, which in this case is 3.

1/3x + 5/3x = 20
(1 + 5)/3x = 20
6/3x = 20
2x = 20

Now, we can solve for x by dividing both sides by 2:

2x/2 = 20/2
x = 10

Therefore, the solution to the equation is x = 10.