The art museum had a total of 224 visitors on tuesday. visitors older than 18 paid $12 for admission. visitors 18 years or younger paid $8 for admission. the museum collected a total of $2,520. how many visitors were 18 or younger?

Given:
total of 224 visitors
older than 18  paid $12
18 and below paid $8
total collection 2,520

Let l be visitors older than 18 and m be visitors 18 and below.

l + m = 224
12l + 8m = 2,520

l = 224 - m
12(224 - m) + 8m = 2520
2688 - 12m + 8m = 2520
-4m = 2520 - 2688
-4m = -168
m = -168/-4
m = 42    number of visitors 18 and below.

l = 224 - m
l = 224 - 42 
l = 182 number of visitors older than 18.

12(182) + 8(42) = 2520
2184 + 336 = 2520
2520 = 2520

The first digit is in the middle school 100s place