Afamily went to an amusement park and paid $12 for each adult and $8 for each child. a group of 15 people went to the park and it cost $140. this system of equations models this situation, where x is the number of adults and y is the number of children.
how many children were in the group?
x + y = 15
12x + 8x = 140

Yes, very good. correct equations
now simplify the second equation
12x+8y=140
undistribute the 4 in both 8 and 12
4(3x+2y)=140
divide both sides by 4
2x+3y=35

seconde equation
x+y=15
multiply by 2
2x+2y=30

compare
2x+3y=35
2x+2y=30
make the secondn one negative and add
2x+3y=35
-2x-2y=-30  +
0x+1y=5
y=5
subsiutte
x+y15
x+5=15
subttract 5
x=10

10 adults
5  kides