Hi, Siyasi2 ! Let x = the number of hot dogs, y = the number of chips, and z = the number of drinks. Then we know:
5x + 4y + 5z = 15.75
x = y + 0.75
z = 2x - 1
Let's substitute the 3rd equation into the first one.
5x + 4y + 5(2x - 1) = 15.75
5x + 4y+ 10x - 5 = 15.75
15x + 4y = 20.75
Now, let's re-write the 2nd equation as x - y = 0.75
We now have a system of two equations with two unknowns.
15x + 4y = 20.75
x - y = 0.75
To solve this, we can multiply the bottom equation by 4 and add.
15x + 4y = 20.75
+ 4(x - y = 0.75)
19x = 23.75
or x = 1.25
If x = 1.25, then using the one of the equations above, we can solve for y.
x - y = 1.25 - y = 0.75
.50 = y
Since z = 2x - 1, then z = 2(1.25) - 1 = 2.5 - 1 = 1.50
So, a hot dog is $1.25, chips are 50 cents, and a soft drink is $1.50. Please let me know if you have any questions.
