How I stopped an Alien Invasion using Proportion

I saw an ALIEN walking alone... I talked to him, and he ask me to do a favour.. that favour was to do 3 question from the text book.

Question # 8.
Determine the missing value.
a.) 2 10 b.) 2 14 c.) 30 6 d.) 3 12
-- = -- -- = -- -- = -- -- = --
3 15 5 35 45 9 4 36

Question # 16.
A gardener take a half hour to mow and weed a lawn that measures 20m by 15m, He charges $25 per hour. How much should the gardener receive for a lawn that measures 40m by 30m?
- 20m by 15m is $25 per hour.
- 40m by 30m would cost $50, Because 20 x 2 = 40 and 15 x 2 = 30.
- The cost of 40m by 30m will be $50

Question # 21.
David can saw a log into three pieces in 7min. If he continues sawing at a constant rate, how long will it take him to saw a similar log into six pieces?
minutes / pieces
7 minutes/3 = 3.5 3/3 = 1
3.5 x 6 = 14min 1 x 6 = 6

- It will take David 14 minutes, to saw six pieces of log.