Question

Find the value of x+y if 8x+7y=11 and 7x+8y=4​

Answer 1

Answer:

Given,

8x+7y=11-------1

7x+8y=4-------2

Adding 1 and 2,we get

15x+15y =15

15(x+y)=15

Therefore,x+y=15

Answer 2

Answer:

x + y = 1

Step-by-step explanation:

8x + 7y = 11    (let this be equation 1)

⇒ $x=\frac{11-7y}{8}$  (let this be equation 2)

7x + 8y = 4  (let this be equation 3)

now substitute equation 2 in equation 3

⇒ $7(\frac{11-7y}{8} )+8y=4$

⇒ $\frac{77-49y}{8} +8y=4$

⇒ $\frac{77-49y+64y}{8} =4$

⇒ $77+15y=8*4$

⇒ $15y=32-77$

⇒ $y=\frac{-45}{15}$

⇒ $y=-3$

Now substitute the value of y in equation 1

⇒ $8x + 7y = 11$

⇒ $8x+7(-3)=11$

⇒ $8x-21=11$

⇒ $8x=11+21$

⇒ $8x=32$

⇒ $x=\frac{32}{8}$

⇒ $x=4$

Need to find

→ x + y

⇒ 4 + (-3)

⇒ 4-3

⇒ 1

∴ x + y = 1

Hope this helps you❤❤❤