y varies directly with x" means y = constant * x or y = kx ----- (1)1. when x = -1/2, y = 2Put it in (1):2 = k * (-1/2)multiply by 2:4 = k * (-1)4 = -kk = -4y = -4x
"find the value of y when x= -0.3"y = -4x = (-4) * (-0.3) = 1.2
So for each problem, start with y = kxThey give you one x and one y value.Put it in y = kx and find k.Then put x = -0.3 and find y.
