Correct. A system is consistent if it has at least one solution. This will be the case if the two lines intersect or if the graphs of the two equations are the same line. Since there is only one line, this line is the graph of both equations. One point through which the line passes is $\displaystyle{\left({5},{0}\right)}\usepackage{cmbright}\Huge\$ . This means that $\displaystyle{2}{\left({5}\right)}+{2}{\left({0}\right)}=?\usepackage{cmbright}\Huge\$ , so the missing number is 10.