Answer:
Child attend: 58
Studen attend: 80
Adult attend: 29
Explanation:
a + c + s = 167 Eq. 1
12a + 5c + 7s = 1198 Eq. 2
a = c/2 Eq. 3
a = adult attend
c = children attend
s = students attend
Replacing Eq, 3 in Eq. 2:
12(c/2) + 5c + 7s = 1198
6c + 5c + 7s = 1198
11c + 7s = 1198
7s = 1198 - 11c
s = (1198 - 11c) / 7 Eq, 4
Replacing Eq, 3 and Eq, 4 in Eq, 1
c/2 + c + (1198-11c) / 7 = 167
7c/14 + 14c/14 + 2(1198-11c)/14 = 2338/14
7c/14 + 14c/14 + 2396/14 - 22c/14 = 2338/14
7c + 14c + 2396 - 22c = 2338
7c + 14c - 22c = 2338 - 2396
-1c = -58
c = -58/-1
c = 58
from Eq. 3
a = c/2
a = 58/2
a = 29
from Eq. 4
s = (1198-11c)/7
s = (1198 - 11*58)/7
s = (1198 - 638) / 7
s = 560/7
s = 80
Check:
from Eq, 1
58 + 29 + 80 = 167