80 POINTS Which properties justify the steps taken to solve the system?

{2a+7b=03a−5b=31

Drag the answers into the boxes to match each step.

10a+35b=0; 21a−35b=217
​31a = 217
a = 7
2(7)+7b=0
14 + 7b = 0
7b=−14
b=−2