Which best explains or justifies Step 1?
subtraction property of equality
completing the square
factoring out the constant
zero property of multiplication

Two spray paint machines are used to paint different portions of a large wall. the first machine (nicknamed "paint pro") is used for two hours. the second machine (nicknamed "goldilocks") is used for an hour and a half. when they are working at the same time, they can paint 55 square feet per minute. together they painted 5850 square feet of wall. how many square feet of wall per minute can each machine paint? e used to paint different portions of a large wall. the first machine (nicknamed "paint pro") is used for two hours. the second machine (nicknamed "goldilocks") is used for an hour and a half. when they are working at the same time, they can paint 55 square feet per minute. together they painted 5850 square feet of wall. how many square feet of wall per minute can each machine paint?