Associative property of multiplication which states :
(a * b) * c = a * (b * c)
I am using "x" but alphabet letter does not matter.
#9
Words: x is greater than or equal to -4
Algebra: x ≥ -4
Possible solutions: 0,1,2
#13
Words: x is greater than 0
Algebra: x > 0
Possible solutions: 1,2,3