Number of solutions of pair of linear equations

Compare ratios of coefficients: $\frac{a_1}{a_2} = \frac{5}{3}$ $\frac{b_1}{b_2} = \frac{-15}{-9} = \frac{5}{3}$ $\frac{c_1}{c_2} = \frac{8}{24/5} = \frac{40}{24} = \frac{5}{3}$ Since $\frac{a_1}{a_2} = \frac{b_1}{b_2} = \frac{c_1}{c_2}$, the lines are coincident and have infinitely many solutions.