Question

If 7x + 13y =35 and 13x + 7y = 25 then x + y = ________​

Answer 1

Answer:

3

Step-by-step explanation:

Add both the equations :

20 x + 20 y = 60

Therefore, x + y = 3

Answer 2

7x + 13y = 35 ___(i) × 13

13x + 7y = 25 ___(ii) × 7

By elimination method;

 91x + 169y = 455

- 91x ±  49y = -175

---------------------------

120y = 280

y = 7/3

Putting value of y in (i) equation;

7x + 13 (7/3) = 35

7x = 35 - 91/3

7x = (105 - 91)/3

x = 14/(7 × 3)

x = 2/3

To find: x + y

i.e.,

2/3 +7/3

= 9/3

= 3