let x = number of adults let y = number of children
There are 30 people in the group, so x+y = 30
The total cost is $175, so 10x + 5y = 175
10x + 5y = 175 Divide by 5: 2x + y = 35
Now subtract the two equations: 2x + y = 35 x + y = 30 x = 5
Substitute x into one of the equations to find y.
5 + y = 30 y = 25
Now plug both values into the other equation to check your work.
2(5) + 25 = 35 10 + 25 = 35 35 = 35