If a number equals sixteen when it’s divided by 4, then we know that number is the 16 times four. Or expressed algebraically:
if: x / 4 = 16
then: x = 16 × 4
One way you could work this out, if you couldn’t do it in your head would be to treat both sides of the equals sign as separate groups. One group is (x / 4), and the other group is (16). What you want to do is to get x all alone in a group, so how do we turn (x / 4) into just an x on it’s own? Simple, we multiply it by 4. Now, whatever you do to one group, you have to do to both (or else you’re changing the equation), so if we multiply the second group by 4 as well, we get (x) in one group, and (16 × 4) in the other, or x = 16 × 4.
Then it’s simply a matter of working out what 16 × 4 is, and that’s 64. So x = 64.
