Question 669634
Determine which property was used.

1. {{{ 1*7 = 7}}}


2. {{{-7y =-7y}}}


3. If {{{10 = y}}}, then {{{y = 10}}}.


4. {{{x + 0 = x}}}


5. If {{{2(a + b) = 3c}}}, and {{{a + b = 9}}}, then {{{2(9) = 3c}}}.


6. {{{2 = x}}}, so {{{2 + 5 = x + 5}}}


7. If {{{x+2=10}}}, then {{{x+2+(-(2))}}} equals {{{what}}}, and {{{why}}}?


8. {{{(x-3)(x + 4) = 0}}}, so {{{x = 3}}} or {{{x =-4}}}.


9. {{{4x = 8}}}, so {{{x = 2}}}


10. {{{x + (-(x)) = 0}}}


11. {{{( 3/3 )( 2/5 ) + ( 5/5 )( 4/3 ) =  6/15 +  20/15}}}


12. If {{{5x = 0}}}, what is {{{x}}}, and {{{why}}}?


13. If {{{3x + 2 = y}}} and {{{y = 8}}}, then {{{3x + 2 = 8}}}.


14. If {{{x = 3}}} and {{{y =-4}}}, then what does {{{xy}}} equal, and{{{ why}}}?


15. Can {{{x < x}}}? {{{Why}}} or {{{why}}}{{{ not}}}?