Question

Pls help meeeeeeeeeeeeee

Answer 1

the right answer is:

• (A)
  `2+(1)/(2)a`

Explanation:

You take the equations that the exercise give you:

1. x + y = 4
2. x - y = a

Now you clear the "y" variable in any equation you want, in this case, I'm gonna use the second equation:

• x - y = a
• -y = a - x

3. y = x - a

And now, you'll replace this third equation in the equation you didn't take (the first in this case).

• x + y = 4
• x + (x - a) = 4
• x + x - a = 4

Add the x variables:

• 2x - a = 4
• 2x = 4 + a
• x = (4 + a) / 2

That's the answer of the exercise, but you can represent this in this form:

• x = (4 + a) / 2 ↔
  `x = (4)/(2) + (1)/(2) a`

• x = (4 + a) / 2 ↔
  `x = 2+ (1)/(2) a`

By this reason, the right answer is
`x = 2+ (1)/(2) a`.