From point a and b, the distance between which is is 30km, two people heading toward each other that left at the same time meet in 3 hours and 20 min. if the first person where to leave 2 hours ahead the other, then they would have met in 2.5 hours after the second person had left. what is the speed of the two people

Simonne used the following steps to simplify the given expression. 12-3(-2x+4) step 1: 12+(-)+(-3)(4) step 2: 12+6x+(-12) step 3: 12+(-12)+6x step 4: 0+6x step 5: 6x what property of real numbers was used to transition from step 3 to step 4? •identity property of addition •inverse property of addition •associative property of addition •commutative property of addition