AYO can anyone solve and give a explaination plz? its for a friend

One side of a rectangle is 7 feet shorter than seven times the other side. find the length of the shorter side if we also know that the perimeter of the rectangle is 306 feet.

Ben is three times as old as samantha, who is two years older than half of michel's age. if michel is 12. how old is ben?

A6 ounce bottle of dressing costs $1.56 a 14 ounce bottle costs $3.36 a 20 ounce bottle costs $5.60 which has the lowest cost per ounce