Question

Solve the following word problem by using a system of equations.

Answer 1

For this problem, we can use systems of equations. I will use the variables x  (for ice-cream) and y (for soda). We get the system:

2.25x+0.75y=30.00
x+y=18

Putting the second equation in terms of y, we get that y=-x+18. We can substitute this into our first equation.

2.25x+0.75y=30.00
becomes
2.25x+0.75(-x+18)=30

Solving for x, we get that x=11. This satisfies answer B.

However, if you want to check to see if this is correct, you could find y by plugging in your value of x into the first equation, then check to see if your found values satisfy BOTH equations.

2.25(11)+0.75y=30
24.75+0.75y=30
0.75y=5.25
y=7

Then we plug this into both equations to see if they are true.

2.25(11)+0.75(7)=30
24.75+5.25=30
30=30 (This is true)

x+y=18
11+7=18
18=18 (This is true).

Both equations are true, so the value for x and y are correct. We see that only answer B is supported through analyzing your work.

:)