The cost of three books and 2 pens is rs.395 and the cost of 2 books and 5 pens is rs.355.find the prices of a book and a pen

Assume as book to be x and pen to be y.

3x+2y=395 equation 1

2x+5y=355 equation 2

Make any variable either x or y to be equal.

3x*2+2y*2=395*2

2x*3+5y*3=355*3

Here, I am making x as same so I cross multiplied

6x+4y=790 equation 3

6x+15y=1065 equation 4

Put minus sign in any one of the equation 3 or equation 4 in order to cancel out x.

6x+4y=790

-6x-15y= -1065

0 - 11y= - 275

y= - 275/ - 11

y= 25

As we got y, we can put the value of y in equation 1 or equation 2.

3x+2y=395

3x+2*(25)=395

3x+50=395

3x=395-50

3x=345

x=345/3

x=115

As we assumed the book to x and pen to be y

price of book = Rs. 115

price of pen= Rs. 25

answer;

the correct answer

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have a nice day < 3

yes. we do proportions in probabilities.