\[ \text{The Investment Multiplier (K) is given by}\quad K = \frac{1}{1 - MPC} \]
\[\text{So, } MPC = 1 - \frac{1}{K} = 1 - \frac{1}{5} = 0.8.\]
\[\text{Since } MPC + MPS = 1, \text{we get } MPS = 1 - 0.8 = 0.2.\]
\[\text{The savings function is: } S = -C + MPS \times Y.\]
\text{The options provide the constant term as } -60.
\text{So, the relevant saving function is: } S = -60 + 0.20Y.