If y varies directly as x, this means that y is directly proportional to x, or in other words, y = kx, where k is a constant of proportionality.
To find the value of k, we can use the information given in the problem: when x is 6, y is 48. Substituting these values into the equation, we get:
48 = k * 6
Solving for k, we get:
k = 8
Now that we know the value of k, we can use the equation y = kx to find the value of y when x is 2:
y = 8 * 2 = 16
Therefore, the expression that can be used to find the value of y when x is 2 is y = 8x, which gives y = 16 when x is 2.