The variable x is twice the value of the variable y and the sum of x and y is 42 solve for x and y.

Write two equations with the given information:

1) x = 2y ( x is twice the value of y)

2) x + y = 42

Replace x in the second equation with the value of x in the first equation:

2y + y = 42

Simplify:

3y = 42

Divide both sides by 3:

y = 42 / 3

y = 14

Now we have the value for Y, solve for x by replacing y with 14:

x = 2y

x = 2(14)

x = 28

X = 28 and y = 14

x=28     x=14

Step-by-step explanation:

x+y=42

2y=x

My method of doing this is a little unorthodox so this is probably going to make no sense... but here goes...

42/2=21

21*(2/3)=14

14*2=28

you didn't post any answer choices, so its not 100% clear what your teacher is looking for

however, log(15/7) is equivalent to log(15) - log(7)

i'm using the rule log(x/y) = log(x) - log(y)