The answer is $103.
To determine how much Eileen will spend on gasoline, first we need to calculate how many gallons she needs.
If she drives 850 miles and her car gets 23 miles per gallon, we can use the proportion:
850 miles : x gallons = 23 miles : 1 gallon
Crossing the products:
x = 850 miles × 1 gallon ÷ 23 miles
x = 36.96 gallons
Thus, Eileen needs 36.96 gallons of gas. If the cost per gallon of gas is$2.79, using the proportion:
36.96 gallons : x = 1 gallon : $2.79
x = 36.96 gallons × $2.79 ÷ 1 gallon
x = $103.12
x ≈ $103