An ordered pair (a,b) is a solution of an equation when substituting a in place of x results in y=b. In the same way, if we substitute b in pace of y then the result must be x=a. So let's take each ordered pair and substitute the non missing value in place of the corresponding variable.
First we have (?,0) which means that we must take y=0 in the equation:
[tex]\begin{gathered} -2x-5y=30 \\ -2x-5\cdot0=30 \\ -2x=30 \\ x=\frac{30}{-2} \\ x=-15 \end{gathered}[/tex]This means that the first ordered pair is (-15,0).
Then we have (0,?) so:
[tex]\begin{gathered} -2x-5y=30 \\ -2\cdot0-5y=30 \\ -5y=30 \\ y=\frac{30}{-5}=-6 \end{gathered}[/tex]So the second ordered pair is (0,-6).
The third one is (?,-2):
[tex]\begin{gathered} -2x-5y=30 \\ -2x-5\cdot(-2)=30 \\ -2x+10=30 \\ -2x=30-10=20 \\ x=\frac{20}{-2} \\ x=-10 \end{gathered}[/tex]Then the third ordered pair is (-10,-2).
