Answer:
See below.
Step-by-step explanation:
A proportion is setting two ratios equal to each other.
Look at the info you are given for price in $ and area in sq ft:
$385 for 70 sq ft
That allows you to write a ratio. The ratio of dollars to square feet is
385/70 (notice it's dollars divided by sq ft)
Now you look at the part of the problem that has an unknown, and you set up the same type of ratio (dollars to sq ft) using x for the unknown.
x dollars to 200 sq ft
The ratio is
x/200 (notice that, again, it's dollars divided by sq ft)
In both cases the ratios are dollars to sq ft.
To set up a proportion, you just set the ratios equal to each other.
385/70 = x/200
Now we solve the proportion. We can cross multiply.
385/70 = x/200
70x = 385 * 200
70x = 77,000
x = 1100
They would charge $1100 to install 200 sq ft of tile.
The unit price is obtained by dividing a cost by the corresponding area in sq ft. you can use either ratio.
unit price = ($385)/(70 sq ft) = $5.5/sq ft
($1100/200 sq ft also works since it is also equal to $5.5/sq ft)
