Question

Which properties justify the steps taken to solve the system? {2+7b=0

Answer 1

Step 1
Multiplication property of equality
Multiplying the first equation by 5 and the second equation by 7

Step 2
Addition property of equality
Adding the two equations you get 31a =217

step 3
Division property of equality
 Dividing both sides of the above equation by 31 to get the value of a

step 4
Substitution property of equality
Substituting a with 7 in the first equation

step 5 
Simplify
simplifying the equation got above 

step 6
 Using associative property of addition by taking 14 to the other side of the equation.
 
step 7
 Division property of equality
Dividing both side of the equation by 7 to get the value of b