You cross multiply here are some exampes
Are these proportions
1. 2 6
----= ---- 2*9=3*6
3 9 18=18 yes this is a proportion
2. 10:5=40:20 10*20 = 5*40
200 =200 yes this is a proportion
3. 4 20
---=--- 4*18=3*20
3 18 72=60 No this is not a proportion
If you are trying to find the missing number
4. 6 n
---= --- 15*n=6*25
15 25 15*n=150
15n=150
15n= 150
---- -----
15 15
n=10
