X/100 = 30/100
Do cross products
80 times X is 80x
100 x 30 is 3000
80x = 3000
Isolate X by circling it
Then divide 80 by both sides
80 divided by 80 is 1
Cross that out
3000 divides by 80
Make a shortcut.
Cross out the 0 in 80 and ONE 0 in 3000
Now it’s 300 divided by 8
300 divided by 8
Can’t divide 3 by 8
So divide 30 by 80
Closest you can get is 8 x 3 which is 24
30-24 is 6
Bring down the 0
60
Now, 60 divided by 8 gives you a decimal
But that doesn’t mean you stop there
8 x 7 = 56 which is the closest you can get
So 60 - 56
4
Make a decimal point
Add a 0 to 300
Bring down the 0
40
8 can go into 40, 5 times.
You end up with X being equal to 37.5%