16 men can reap a field in 30 days. In how many days will 20 men reap the field?

Two poles, 15 m. and 30m. high are 36m. apart. The distance between their tops is

The average of three numbers is 15. If two numbers are 7 and 28 the third is

3¾ of 1280 + .......... = 250% of 2000

7200 ÷ 18 × 0.2 is equal to

If n (A) = 20; n (B) = 8; n (A ∪ B) = 28, then n (A ∩ B) is