R = rides
S = sodas
6R + 3S = $21.75 —> -12R - 6S = -43.5
10R + 6S = $39.50–>10R + 6S = 39.5
Multiplying Justin’s whole equation by -2 will bring out the 6S’, so we can focus on the cost of one ride.
-2R = -4
Divide both sides by -2
So for one ride, it would cost $2.
To find the cost for one soda, we plug in the cost for a ride.
6(2) + 3S = $21.75
12 + 3S = $21.75
3S = $9.75
So for one soda, it would cost $3.25.
