Answer:
2.25
Explanation:
let x be cost of a hotdog 
let y be cost of hamburger 
 
so, 
 
5x + 4y = 17.75 eq. 1 
4x + 5y = 18.25 eq. 2 
 
manipulate eq. 1 so solve for x: 
 
5x = 17.75 - 4y 
 
x = 17.75/5 - (4/5)y 
 
x = 3.55 - (4/5)y eq. 3 
 
substitute eq. 3 to eq. 2: 
 
4(3.55 - (4/5)y) + 5y = 18.25 
 
14.2 - (16/5)y + 5y = 18.25 
 
14.2 + (9/5)y = 18.25 
 
(9/5)y = 18.25 - 14.2 
 
4.05= (9/5)y 
 
y = 2.25 
 
x = 3.55 - (4/5)(2.25) 
 
x = 1.75 
 
hotdog costs $1.75 
hamburger costs $2.25