Find the polynomial that models the problem and use it to estimate the quantity.
1. A rectangle has a perimeter of 8x2+7x3+6x+7 and a length of x. Find the width of a rectangle when the length is 18 feet.
2. Cho is making a rectangular garden, where the length is x feet and the width is 4x – 1 feet. He wants to add garden stones around the perimeter of the garden once he is done. If the garden is 4 feet long, how many feet will Cho need to cover with garden stones?