Answer:
r = cost of rollercoaster = 6
f = cost of ferris wheel=4
g = cost of graviton=8
Step-by-step explanation:
r = cost of rollercoaster
f = cost of ferris wheel
g = cost of graviton
r+f = 10
g+f = 12
r+g = 14
Take the third equation and subtract the first equation
r+g =14
-r-f = -10
-------------------
g-f = 4
Take this and add it to the second equation
g-f = 4
g+f = 12
-------------------
2g = 16
Divide by 2
g = 8
Now find f
g+f = 12
8+f = 12
f = 12-8
f=4
Now find r
r+g =14
r+8 =14
r = 14-8
r = 6