Question

If 8x - y = 11 and 7x - 8y = 4, then what is the value of x + y?​

Answer 1

Answer:

$8x - y = 11 \: \: \: \: \: \: (1) \\ 7x - 8y = 4 \: \: \: \: \: \: \: \: \: \: \: \: (2)$

multiply by -8 to equation ( 1).

-64x+8y=-88. (3)

add equation (2) and(3) we get,

-57x=-84

x=84/57.

put this value of x in equation (1)

8(84/57)-11=y

y=(672/57)-11=45/57

y=45/57

x+y=(84/57+45/57)=129/57

x+y=129/57