Question

If 4x+3y=24 and 3x+4y=25 then find the value of x+y?

Answer 1

Step-by-step explanation:

use elimination method

let 4x+3y=24 be eq 1 and

3x+4y=25 be eq 2

multiply eq 1 by 3 and eq 2 by 4

so the eq will become

12x+9y= 72

12x+16y=100

subtract them

-7y=-28

y=4

put the value of y in eq 1

4x+3(4)=24

4x+12=24

4x=12

x=3

x+y=?

3+4=7

Answer 2

Answer:

The value of x + y = 7

Step-by-step explanation:

Given equations  

         4x+3y=24 _ (1)  

         3x+4y=25 _(2)  

here we need to solve (1) and (2)

multiply (1) with 3  ⇒  3(4x+3y) = 3(24)

                              ⇒ 12x + 9y = 72 _(3)

multiply (2) with 4 ⇒  4 (3x+4y) = 4(25)

                              ⇒  12y + 16y = 100 _(4)  

subtract (3) from (4)

     ⇒  12x + 16y - (12x + 9y) = 100 - 72

     ⇒  12x + 16y - 12x - 9y  = 28  

     ⇒   7y = 28

     ⇒   y = 4

substitute y = 4 in (1) ⇒   4x+3(4)=24

                                        4x + 12 = 24

                                        4x = 24 - 12 = 12

                                        4x = 12 ⇒ x = 3

x = 3, y = 4

x + y = 3 + 4 = 7