Simple Formula with Relative and Absolute Addressing $y = m x + b$

Simple formula with relative and absolute addressing.The following worksheet computes values of $y = m x + b$
a.What is the formula using relative addressing in A5?
b.What is the formula using relative and absolute addressing in B7?
$$\begin{array} { | c | c | c | } \hline & A & B \\\hline 1 & m = & b = \\\hline 2 & 2 & 1 \\\hline 3 & & \\\hline 4 & x & y \\\hline 5 & 0 & 1 \\\hline 6 & 1 & 3 \\\hline 7 & 2 & 5 \\\hline 8 & 3 & 7 \\\hline\end{array}$$