So for this, you will be doing a system of equations. The first equation will be how much you spent and the second equation is how much they advertise.
Let h = cost of hotdog and d = cost of drinks
[tex] 10h+5d=35\\ 7h+4d=25.25 [/tex]
With this, i'll be using the substitution method. So firstly, subtract 10h on each side of the first equation. It will look like this: [tex] 5d=35-10h [/tex]
Next, divide 5 on each side of the first equation. Your answer will be [tex] d=7-2h [/tex]
Next, replace d in the second equation with (7-2h). Your second equation will look like this: [tex] 7h+4(7-2h)=25.25 [/tex] . From here you can solve for h.
Firstly, foil 4(7-2h). [tex] 7h+28-8h=25.25 [/tex]
Next, combine like terms: [tex] 28-h=25.25 [/tex]
Next, subtract 28 on each side to get [tex] -h=-2.75 [/tex]
Lastly, multiply -1 on each side of the equation to get [tex] h=2.75 [/tex]
Now that we got h, we can solve for d by substituting 2.75 in the h variable in either equation. For this, I'll be using the first one.
[tex] 10(2.75)+5d=35\\ 27.5+5d=35\\ 5d=7.5\\ d=1.5 [/tex]
In short, hotdogs are $2.75 each and drinks are $1.50 each.