David W. answered 04/28/16
Tutor
4.7
(90)
Experienced Prof
Let x = number of adult tickets
y = number of children tickets
z = number of senior tickets
Translate:
“the theater sold 222 tickets” means x + y + z = 222 [eq1]
“took in $1383” means
money rom + money from + money from = $1383
adult tickets children tickets senior tickets
7x + 5y + 4z = 1383 [eq2]
{note: For each class of ticket: money = (cost per ticket)*(number of tickets)]
“twice as many adults tickets were sold as the total of children and senior tickets” means
x = 2(y+z) [eq3]
Now, the math:
2x + 2y + 2z = 444 [this is eq1*2]
2x + (2y + 2z) = 444 [now, look at eq3 as x = 2y + 2z]
2x + x = 444
3x = 444
x = 148
There were 148 adult tickets sold.
Now, eq1 becomes:
148 + y + z = 222
y + z = 74 [eq4]
And, eq2 becomes:
1036 + 5y + 4z = 1383
5y + 4z = 347
4y + 4z = 296 [this is 4*eq4]
---------------------------- [elimination; subtract equations]
y = 51
There were 51 children’s tickets sold.
And now, eq1 is:
148 + 51 + z = 222
z = 23
There were 23 senior’s tickets sold.