28 books weigh 31 lbs. how much 45 weigh?

Question

Question

 

28 books weigh 31 lbs. how much 45 weigh?

Answer 1

or use a ratio: 

"28 is to 31lbs , as WHAT? is to 45 lbs."   We write this mathematically as:

 

28/31 = X/45

X = 28/31*45 = 1260/31 = 40.64516.......

Answer 2

Calculate weight of each book:  28 books/31 lbs = 0.903 lbs

45 books x 0.903 lbs/book = 40.65 lbs