If y varies directly as x and y is 18 when x is 5 which expression can be used to find the value of y when x is 11?

y = kx  where k is a constant   Thats direct variation.

plug in given values:-

18  = k * 5

k = 18/5 = 3.6

so the equation of variation is y = 3.6x

when x = 11, y = 3.6 * 11 =  39.6  Answer