Tickets to the museum cost $18 for adults and $12 for children. a group of 20 people went to the museum, and the tickets cost $324. the system of equations models this situation, where x is the number of adults and y is the number of children.
x+y=20
18x+12y=324
how many adults and how many children were in the group?
a.
8 adults and 12 children
b.
10 adults and 10 children
c.
12 adults and 8 children
d.
14 adults and 6 children

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.

correct

step-by-step explanation: