We will be able to calculate the percentage change in LB , BH & LH but we cant add 2 percentage of different bases.

Let the cost price of the article be Rs.100.

Let the List price of the article by "x".

Then, when the merchant offers a discount of 30%, the merchant will sell the article at x - 30% of x = 70% of x = 0.7x. .......(1)

Note: Discount is measured as a percentage of list price.

The loss made by the merchant when she offers a discount of 30% is 16%. 

Therefore, the merchant would have got 100 - 16% of 100 = Rs.84 when she offered a discount of 30%. .......(2)

Note: Loss is always measured as a percentage of cost price.

Therefore, equating equations (1) and (2), we get

0.7x = 84

or x = 120.

If the list price is Rs.120 (our assumption of cost price is Rs.100), then when the merchant offers a discount of 10%, she will sell the article at 

120 - 10%o of 120 = Rs.108.

As the cost price of the article was Rs.100 and the merchant gets Rs.108 while offering a discount of 10%, she will make a profit of 8%.

The best way to solve this problem is by using the concept in Mixtures and Alligation. 

Vijay earned a total income of Rs.7000 for his investment of 50,000.

Therefore, his average rate of return = 7000/50000 * 100 

By rule of alligation, if the value of one of the products is 10 (cheaper) and the other is 15 (dearer) and if the two are mixed such that the average value of the mixture is 14 (mean price), then the two products have been mixed in the following ratio.

The ratio of

Cheaper product : Dearer product 

(Dearer product price - mean price) : (Mean price - cheaper product price)

In our example, the cheaper product is the investment at 10%, the dearer product is the investment at 15% and the mean price is the average return of 14%.

Therefore, the amount invested @10% interest = 1/5 * 50,000 = 10,000.

2x + 8 = 3x = 6x – 4 –2x – 8

    8-x = 4x – 12

    x = 4

    Sum of 10 terms = 10 (2*12+9*4)/2 = 300

Solution: From 1 to 100, we have number like 3, 13, 23, 33 etc. which are 10 in number. Then number 30 to 39 have one 3 extra each giving 10 threes. So, upto hundred, we have 10 + 10 = 20 threes. Since we have 700 pages we have number of 3’s as 7x20 = 140 Then all the 100 numbers from 300 to 399 have one 3 extra each giving a hundred 3’s So totally, 240 threes. Choice (1)