The pressure $P$ (in pounds per square foot), in a pipe varies over time. Three times an hour, the pressure oscillates from a low of 80 to a high of 220 and then back to a low of 80. The pressure at time $t = 0$ is 80. Let the function $P = f(t)$ denote the pressure in pipe at time $t$ minutes.

Find a possible formula for the function $P = f(t)$ described above.

$f(t) =$ help (formulas)