Answer:
1)12a-5a = (12-5)a = 7a (using distributive property)
2)(7a)b = 7(ab) = 7ba (using associative property and the commutative property)
3)8+5 = 5+8 (using commutative property)
4)-4(1) = -4 (using identity property of multiplication)
5)25+(-25) = 0 (using additive inverse property)
6)([-2] + [1]) +3= -2 + (1+3) (using associative property of addition)
7)(2x5)x7= 2x(5x7) (using associative property of multiplication)
8)5x(8+5)= 5x8 + 5x5 (using distributive property)
9)-9(9) = -81 (using multiplication property of -1)
110)3x⅓= 1 (using multiplicative inverse property)