Solve the Problem
-Let $x$ Represent the Number of Gallons of Gas Sold At

Multiple Choice

Solve the problem
-Let $x$ represent the number of gallons of gas sold at $\$ 2.10$ per gallon, and let $y$ represent the total cost of the gasoline (in dollars) . Write an equation for this situation. Then give the ordered pair with an $x$ -value of 18 associated with this equation.

A) $x=2.10 y ;(18,8.57)$
B) $x=2.10+y ;(18,15.90)$
C) $y=2.10 x ;(18,37.80)$
D) $y=2.10+x ;(18,20.10)$