If you need to write a function (e.g., P(t)=20-14e^(-0.024t) ) rewrite it as an equation (e.g., y=20-14e^(-0.024t) ), since the general functional notation is not supported and an entry of P(t) will be interpreted as the variable 'P' multiplied the variable 't', in parentheses. 

When typing 'e', user the 'e' from the virtual keyboard otherwise it will be interpreted as variable.

Since you need to find P(t) for t = 3, that is p(3), simply plug the value for 't' into 20-14e^(-0.024t) and click on 'Solve'.

Click here to see the solution.

After 3 months the pole will be 6.97 meters high.

If you need to graph the function, select the 'Graph' tab, type  y=20-14e^(-0.024t) and click on 'Solve'.

Click here to see the graph.