Question

Y varies directly with x, and y = 7 when x = 2. What is the value of y when x = 5?

Answer 1

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.