Answer:
x = [tex]\frac{4}{5}[/tex]
Step-by-step explanation:
since the variables are in proportion then the equation relating them is
y = kx ← k is the constant of proportionality
to find k use the given condition, y = 15 when x = 3
k = [tex]\frac{y}{x}[/tex] = [tex]\frac{15}{3}[/tex] = 5, hence
y = 5x ← is the equation relating x and y
when y = 4, that is
5x = 4 ( divide both sides by 5 )
x = [tex]\frac{4}{5}[/tex]
