2. Example:
2 6
Write the original proportion.
3 9
9 2 6 3 Use the cross product property.
If the cross products are equal, then
18 18
it is a proportion.

3. Example:
2 6
Write the original proportion.
x 9
9 2 6 x Use the cross product property.
18 6x Divide both sides by 6 to isolate the
6 6 variable, then simplify.
3 x

4. If the model is 5 inches tall, how tall is the actual building in
feet? To find the actual height of the building, use the ratio
from the previous step to write a proportion to represent
the question above.
4 inches 5 inches
15 feet x
4 x 5 15 Use the cross product.
4x 75
Isolate the variable, then simplify.
4 4
x 18.75 feet Don’t forget your units.