a=22, c=15, and a+c=11, so we can say:
a=11-c, then we are told that:
22a+15c=228, using a from above in this equation gives us:
22(11-c)+15c=228 carrying out indicated multiplication
242-22c+15c=228 combining like terms on left side
242-7c=228 subtract 242 from both sides
-7c=-14 divide both sides by -7
c=2, since a=11-c
a=11-2
a=9
So there were 9 adults and 2 children in the group.
