A play was attended by 348 people, some adults and some children. Admissions for adults was $1.50 and for children 75 cents. The total amount collected was $390. How many adults attended the play?

172

Step-by-step explanation:

Let adults be x

and children be y

According to the problem,

x + y = 348              . . . (1)

1.5x + 0.75y = $390. . . (2)

From Eq 1, find the value of x:

x = 348 - y

Put this value in Eq 2:

1.5 ( 348 - y ) + 0.75y = 390

522 - 1.5y + 0.75 y = 390

-1.5y + 0.75y = 390 - 522

-0.75y = -132

y= -132/-0.75

y = 176

Put the value of y in Eq 1

x  + 176 = 348

x = 348 -1 176

x = 172

No. of children = 176

No. of adults = 172

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.