To find a percentage you can use the equation:
a × (b/100) = c
Where 'a' is the number we want to find the percentage of (in your case this is the number you don't know),
'b' is the percentage you want to find (in your case this is 6%),
and 'c' is the resulting percentage that's been found (in you case this is 3)
So, since for your equation:
a = ?
b = 6
c = 3
we can put these values into the equation,
a × (b/100) = c
to try and find out what 'a' equals.
a × (6/100) = 3
a × 0.06 = 3
Now you can divide both sides of the equation by 0.06 to find the value of 'a:
(a × 0.06)/0.06 = 3/0.06
a = 50
This means that 3 is 6% of 50.