2a - 3 = 9......
the first thing you would have to do is add a 3 on both sides of the equation.
2a - 3 =9 ------> 2a = 12
+3 +3
Next, divide the 2 out from the a.
2a = 12 ---------> a = 6
/2 2/
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-3(b + 2) = -9
multiply the -3 in the parentheses
-3(b + 2) = -9 -------> -3b - 6 = -9
Add a 6 to both sides
-3b - 6 = -9 --------------> -3b = -3
+6 +6
Lastly divide -3 from both sides
-3b = -3 ----------------------> b = 1
/-3 /-3