If y varies directly as x and y = 12 when x = 8, find y when x = 14.

The direct variation between x and y may be written as,

y = kx

where k is the constant of variation. From the first set of values of the variables,

12 = k (8)

the value of k is 1.5. Substituting the next set to the same equation,

y = 1.5 (14)

The value of y is 21.