To solve this proportion, we need to cross multiply and solve for x.

First, rewrite the proportion as:
6/1 = 4/5 = 3x/0.6

Now, cross multiply:
6 0.6 = 1 3x
3.6 = 3x

Now, solve for x:
x = 3.6 / 3
x = 1.2

Therefore, the value of x is 1.2.