Robert is building a 15 foot long, 10 foot wide, rectangular wooden fence around his garden.  He needs 2 wood slats for every foot of fencing he builds.  How many wooden slats will he need?
What is the solution?
A rectangle has 2 long sides and Robert wants them to be 15 feet long so 2*15 = 30 feet long
A rectangle has 2 short sides and Robert wants them to be 10 feet wide so 2*10= 20 feet wide
Together, he will need 30 feet and 20 feet of fencing so 30+20 = 50 feet of fencing
He needs 2 wooden slats per 1 foot of fencing and he is building 50 feet of fencing so he needs 50*2 = 100 wooden slats