An investor is deciding between two options for a short-term investment. One option has a return R, in dollars, t months after investment, and is modelled by the equation `R=100(3^t)`. The other option has a return R, in dollars, t months after investment, and is modeled by the equation R=350 t. After 4 months, how much less in the return given by the linear model than the return given by the exponential model?