For a direct variation describe how the constant of variation affects whether y increases or decreases as x increases

Equation I 
y=5/2x is indirect variation b'cos as the value of x increases, the value of y decreases and vice versa 

let us substitue x=5, then we get 
y=5/2(5) 
y=1/2 ==> 0.5 

let us substitute x=10, we now get 
y=5/2(10) => 1/4 => 0.25 

Equation II 
y=x+4 

this is direct variation cos as you increase the value of x, the value of y wud also increase and vice versa 

let us substitute different values for x 
let x be 7 
y=7+4 
y = 11 

let x be 2 
y=2+4 
y=6 

thus this is direct variation 

Equation III 
y=4... this is neither cos there is no x..