Question

If 4x+5y=20 and 5x+4y=7 then what is the value of x+y ?

Answer 1

Answer:

x+y=3

Step-by-step explanation:

4x+5y=20............(1)

5x+4y=7................(2)

adding eqiation (1)and (2), we get,

9x+9y=27

=>9(x+y)=27

=>x+y= 3

so, the value of x+y is 3.

I hope it's helpful to you...

Answer 2

Step-by-step explanation:

4x +5y =20[5]

5x +4y = 7[4]

cross multiplication

4x +5y =20 [5]

20x + 25y = 100 (1)

5x + 4y = 7 [4]

20x+ 16y =28 (2)

put equation 1&2

20x + 25y = 100

20x + 25y = 100 20x+ 16y =28

- - -

0 + 9y = 71

9y = 71 -0

9y = 71

y = 71 /9