Answer:
2y² + 3
Explanation:
width of one side is 4y² - y + 6.
two equal sides of rectangle = 2(4y² - y +6) = 8y² - 2y + 12.
perimeter = 2 lengths + 2 widths
12y² - 2y + 18 = 2 lengths + 8y² - 2y + 12
2 lengths = (12y² - 2y + 18) - (8y² - 2y + 12)
= 4y² +6
length = 1/2 (4y² +6)
= 2y² + 3