Question 519248
before A -------------x

At A 40% got down
so balance 60% remained

=0.6x

At B 60$ of 0.6x got down

0.6 *0.6x= 0.36x

Balance = 0.6x-0.36x= 0.24x balance

0.24x=540
x=540/0.24
=2250 before A

----

let total be x

60% are boys

0.6x are boys
0.4x are girls

0.4x=120
x=120/0.4
x=300 total
.-------------

4th- anubhav bought 20 pens at rs 15 & 15 pens at rs 18 per pen . he sold all the pens at 17 rs per pen
find his gain or loss % in whole transaction?
20 pens Rs. 15 => 15*20 = 300
15 pens Rs. 18=> 15*18=270
Total cost = 300+270 = 570
...
Total pens 35 sold at Rs17
= 595

595-575= 20

he made Rs 20 profit on Rs 570 the cost price

so 100*20/570
= 3.5 % profit on cost