Translate into a variable expression the product of p and the sum of p and 12

Can someone answer it, and plot it, for 20 points and brainliest answer? p.s. they're the same ! : )

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.

How many kilograms of a 5% salt solution and how many kilograms of a 15% salt solution must be mixed together to make 45kg of an 8% salt solution?