Question 4869
Whenever this type of problem comes.  Follow the simple steps mentioned below and get the answer.

Define two variables  x and y  (x representing cost of orange and y representing cost of apple)

Now if the cost of 1 orange is x, what is the cost of 2 oranges  ??
YES   it is 2x   and COST of three oranges becomes  3x 

So we can write the following two equations  ---


        4 x + 5 y = 3.56   -----  (1)   
        3 x + 4 y = 2.76   -----  (2)

Now our aim is to solve the two equations to get the value of x and y

We can use the either of the methods  graphical methoid/ elimination method/ or equating the coefficients method

I am explaining the equating the coefficient method here.

We will be multiplying the first equation by  `3`,  which is the coefficient of x in the second equation,    AND multiplying the equation 2 by `4`, which is the coefficient of x in first equation.

        4 x + 5 y = 3.56   -----  (1)   X  3
        3 x + 4 y = 2.76   -----  (2)   X  4


We get     12 x + 15 y = 10.68  -----  (3)   
           12 x + 16 y = 11.04  -----  (4)


On subtracting (3) from (4)  we get
    12 x + 16 y - 12 x - 15 y  =  11.04  - 10.68
        y = 0.36
      
        Substituting the value of y in (1)   or (2) we can get the value of x

(1)  --   4 x + 5 (.36) = 3.56
           4 x + 1.8 = 3.56
           4 x = 3.56 - 1.8 = 1.76
             x = 1.76/4 
             x = 0.44

THIS IS HOW WE SOLVE THE QUESTION.

HOPE IT IS CLEAR TO YOU.  IF YOUR NEED MORE HELP, I AM AVAILABLE FOR ONLINE TUTORING ALSO. YOU CAN CONTACT ME ON kapoorjai1@rediffmail.com