Question

a man purchased 20 atlas for rs. 186000. how many he can buy for rs 145000??

Answer 1

Cost of 1 atlas = total cost/no. of atlas
=186000/20
=Rs9300
No. of atlas which can be bought for Rs145000= Rs145000/Rs9300
=16 atlas(approximately)

Answer 2

Given..
  No.of atlases purchased for Rs.1,86,000= 20 atlases. 
  No.of atlases purchased for Rs.1,45,000= ? 
To find no of atlases purchased for Rs.1,45,000 we shall first find the cost of one atlas... i.e
Cost of one atlas = Cost of no of atlases/ Total atlases. 
                             =  1,86,000/20
                             = 9,300
Cost of 1 atlas= Rs. 9,300

As per the problem.
No of atlases purchased for Rs.1,45,000= Cost of no. of atlases/ Cost of 1 atlas
                                                                   = 1,45,000/9,300
                                                                   = 15.59...
15.59 can be estimated as 16. 
 So 
the man bought 16 atlases for Rs.145000