Hello!
You can make two equations based on what you know
let x stand for the price of 1 hot dog
let y stand for the price of 1 soft drink
6x + 4y = 13
3x + 4y = 8.50
You can subtract the equations from each other to get rid of y
3x = 4.50
Divide both sides by 3
x = 1.50
A hot dog cost $1.50
The answer is $1.50
Hope this helps!