Please get it right, i done this so many times now, i'm running out of points

Ab and bc form a right angle at point b. if a= (-3,-1) and b= (4,4) what is the equation of bc?

If a 36 inch yardstick casts a 21 foot shadow, how tall is a building whose shadow is 168 feet? what is the scale factor

Fatima plans to spend at least $15 and at most $20 dollars on sketch pads and pencils. if she buys 2 sketchpads, how many pemcils can she buy while staying in her price range? fatima can buy between and pencils. ? (type whole numbers. use ascending? order.)