Question

X + y = 12 and y = x - 1. Find the value of 2x + 2y.

Answer 1

Answer: 2x + 2y = 24

Explanation:

x + y = 12

2(x + y = 12)
2x + 2y = 24

So therefore, 2x + 2y = 24

Answer 2

Answer:

2x + 2y = 24

Step-by-step explanation:

You have to isolate y and then use substitution.

x + y = 12       and         y = x - 1        

-x       -x          

y = -x + 12       and         y = x - 1

-x + 12 = x - 1

+x          +x

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

12 = 2x - 1

+1          +1

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

13 = 2x

2x = 13              [ divide both sides by 2]

x = 6.5

Now, you have to plug x (6.5) into y = x - 1.

y = x - 1

y = 6.5 - 1

y = 5.5

Finally, plug both x (6.5) and y (5.5) into 2x + 2y.

2x + 2y

= 2 (6.5) + 2 (5.5)

= 13 + 11

= 24