Writing Linear Equations from Word Problems

At a carnival, ride tickets cost $2 each and game tickets cost $3 each. You can spend $45. Let x represent ride tickets and y represent game tickets. Write the equation Ax+By=C

A pizza place sells large pizzas for $12 and small pizzas for $8.

They sell $500 worth of pizza. Let x = large, y = small. Write the equation Ax+By=C

A school orders markers and erasers. Markers cost $1, erasers cost $3. Their budget is $120. Let x = markers, y = erasers. Write the equation Ax+By=C

You carry math books (3 lbs) and science books (5 lbs). Total: 38 lbs.
Let x = math books, y = science books. Write the equation Ax+By=C

You run small laps (200 m) and large laps (400 m). Total: 3,000 m.
Let x = small laps, y = large laps. Write the equation Ax+By=C

18=2x+3y
If x=3, what is the value of y?

30=3x+2y
If y=6, what is the value of x?

22=2.50x+y
If x=6, what is the value of y?

16=1.5x+2y
If y=5, what is the value of x?

32=2.75x+2y

If x=8, what is the value of y?