
Bradford T. answered 09/26/22
Retired Engineer / Upper level math instructor
Let C, S and A be the number of children, students and adults.
C+S+A=289
A = C/2
C+S+C/2=289
3C+2S = 578 EQN 1
C = (578-2S)/3
5C+7S+12A = 2090
5C+7S+6C=2090
11C+7S=2090 EQN 2
11(578-2S)/3+7S=2090
11(578-2S)+21S=6270
6358-22S+21S=6270
S=6358-6270=88
Substituting 88 into EQN 1
3C+2(88)=578
3C = 578-176 =402
C=402/3=134
A=134/2 = 67
134 Children attended
88 Students attended
67 Adults attended