Answer
a) $\frac{m_1}{m_1+m_2}$
b) The answer is below.
Work Step by Step
a) We know that the acceleration will equal gravity times $\frac{m_1}{m_1+m_2}$. Thus, plot $\frac{m_1}{m_1+m_2}$ on the horizontal axis.
b) To make the plot, enter the data into excel, and then plot the data on a graph. Next, use excel to create the best fit trend-line, and ask excel to write an equation for this line. The slope of this equation will be the value of g.