a$.$ Write down an equation to compute the support reaction $A_m$ as a function of $W,P,L,$& H$.$

b$.$ Compute the value of $P$ that gives a support reaction $A_m$ of $20ft-$kip counterclockwise given the values of $W,L,$ and $H$ in the spreadsheet below.

c$.$ The computed value in cell B$6$ in the spreadsheet below returns an incorrect answer. What is the error? $(A_m$ is assumed to be positive, or counterclockwise, as entered in cell B$6.)$