Reading through the problem we have 3 is, that's 3 equals, what percent, x/100, of 600, times 600.
Notice that for what percent I put X/100. The reason I did this is because the word percent means over 100 and since we don't know what percent we're dealing with yet, we can put a variable there as a placeholder.
So we have 3 = X/100 · 600.
Now cross-canceling the 600 and 100 to 6 and 1, we have 3 = 6x/1.
Multiply both sides by 1 to get rid of the fraction and we have 3 = 6x.
Dividing both sides by 2, we find that 0.5 = x.
So 3 is 0.5% of 600.
