+20 (a) One number is six times another number. The sum of their reciprocals is 2 1/3. Find the two numbers.
(b) 16 men took 9 days to build a 10-km railway track. How long would it take 20 men to build a 25-km railway track?
+37147 a) Two numbers
x and 6x
1/x + 1/6x = 7/3 <==== given , multiply entire equation by x to get
1 + 1/6 = 7/3 x
7/6 = 7/3 x
x = 7/6 * 3/7 = 1/2
the other number is 3
b) 16 m * 9 d / 10 km = 14.4 man days per km
25 km will require 25 * 14.4 = 360 man days if you have 20 men then 18 days required
