Question

At the city museum, child admission is $5.30 and adult admission is $9.40 . On Tuesday, 140 tickets were sold for a total sales of $1086.40 . How many child tickets were sold that day?

Answer 1

Total tickets sold = # of kid's tickets sold + # of adult tickets sold
Total money made = amount of money kid's tickets raised + amount the adult tickets made

These can be rephrased as
140 = k + a
and
$1086.40 = $5.30k + $9.40a

Rephrase the first;
140 = k + a
a = 140 - k

Plug the equation into the first;
1086.4 = 5.3k + 9.4a
1086.4 = 5.3k + 9.4(140 - k)
1086.4 = 5.3k + 1316 - 9.4k
-229.6 = -4.1k
k = 56 tickets

Answer 2

c + a = 140......a = 140 - c
5.3c + 9.4a = 1086.4

5.3c + 9.4(140 - c) = 1086.4
5.3c + 1316 - 9.4c = 1086.4
5.3c - 9.4c = 1086.4 - 1316
-4.1c = - 229.6
c = -229.6 / -4.1
c = 56......so their were 56 child tickets sold