C. Write an equation where y varies directly as x. 1. y=28 when x=7 2. y=30 when x=8 3. y=0.7 when x=0.4 4. y=0.8 when x=0.5 5. y=400 when x=25

(1) y = 4 x(2) y = \dfrac{15 x}{4}(3) y = \dfrac{7 x}{4}(4) x = 250