Answer:
20 is the answer.
Explanation:
1. Make a proportion.
Set the numbers equal to each other.
I chose the numbers 9, 12, 15, and of course x.
Make the fractions in a way that the x is in the numerator if you want to make your life easier.
15/9 = x/12
2. Simplify
Cross multiply the numbers.
This will give you the equation of
9*x and 15*12
3. Make an equation
Simplify the numbers by mulitplying them
9x = 180
4. Divide both sides by 9
9x = 180
/9 /9
x = 20
Hope this helped,
Kavitha Banarjee