Hola, me podrían ayudar

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?

Abag contains 10 white golf balls and 6 striped golf balls. a golfer wants to add 112 golf balls to the bag. he wants the ratio of white to striped gold balls to remain the same. how many of each should he add?

An equation in slope-intersept form the lines that passes thought (-8,1) and is perpindicular to the y=2x-17.