[tex]\frac{1}{4}[/tex] → a
the equation is y = mx ( where m is the slope / constant of variation )
calculate m using the gradient formula
m = ( y₂ - y₁ ) / (x₂ - x₁ )
with (x₁, y₁) = (0, 0 ) and (x₂, y₂ ) = (4, 1) ← 2 points on the line
m = [tex]\frac{1-0}{4-0}[/tex] = [tex]\frac{1}{4}[/tex]
