Question

if 3n+5y = 9 and 5n+3y =7 than the value of n+y is​

Answer 1

Answer:

3n+5y=9-----(1)

5n+3y=7-----(2)

multiplying eq(1) by 5 & eq(2) by 3 we get

15n+25y=45

-15n ± 9y= - 21

_____________

    16y=24

y=  

16

24

​  

=  

2

3

​  

 

[y=  

2

3

​  

] and  n=  

3

9−5n

2

3

​  

 

​  

=  

2

−1

​  

 

Hence[x=  

2

1

​  

]& [y=  

2

3

​  

]

so x+y=  

2

1

​  

+  

2

3

​  

=2

Answer 2

To find the value of n+y .

First we will need to find to find the value of n&y.

3n+5y=9

Multiply whole equation by 5.

5(3n+5y)= (9)×5

15n+25y=45 -----------①

5n+3y=7

Multiply whole equation by 3.

3(5n+3y)=(7)×3

15n+9y=21 -----------②

Subtracting ② from ①

15n+25y= 45

- -

15n+9y = 21

16y=24

Hence y = 24/16 =2/3

Now, Putting the value of y in ②

15n+9y=21

15n+ 9×2/3=21

15n=21 - 6

15n=21 - 6

n=15/15

Hence n=1

Therefore

n+y=2/3+1

=2/3+3/3

=5/3