If it is 0.5 miles from the white house to the washington monument and 1.2 miles from the washington monument to the capitol, how far is it from the white house to the capitol?

Simonne used the following steps to simplify the given expression. 12 - 3(-2x + 4) step 1: 12 + (–3)·(–2x) + (–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? a. identity property of addition b. inverse property of addition c. associative property of addition d. commutative property of addition

Having a hard time understanding this question (see attachment).

Using elimination, what is -4x+2y=-12 4x+8y=-24