Weighted moving average is calculated by multiplying the weights with the forecast values of the previous two years and then by adding them. The higher weight is multiplied with more recent year in the calculation as shown below.

We find the forecasts by starting with the sales values of $2013$ and $2012$ by using $2-$year weighted moving average as shown below:

Hence, the forecast for $2017$ is $141\mathrm{.}82$ which can be rounded to $142$