The ninth grade class has a total of 450 students made up of x girls and y The number of girls minus twice the number of boys is 18. Find the number of girls are in the ninth grade. Which system of equations and solution represent this situation?
Multiple choice question.

A)
x+y=450
and x−2y=18
; There are 234 girls in the ninth grade.

B)
x+y=450
and x−2y=18
; There are 306 girls in the ninth grade.

C)
x+y=450
and 2x−y=18
; There are 156 girls in the ninth grade.

D)
x−y=18
and 2x−y=18
; There are 162 girls in the ninth grade.