The sum of three numbers is 6. The first number minus the second number is -7. Twice the second number is 10.

Answer 1

x + y + z = 6

x - y = -7

2y = 10

y = 5

x - 5 = -7 → x = -2

-2 + 5 + z = 6

What is the value of z?

Answer 2

First you want to set up the following system of equations(set of equations) that mimic the verbal cues given as follows:

"The sum of three numbers is 6" => x+y+z=6. Just replace the unknown "numbers" with variables.

"The First Number minus the Second Number is -7" => x-y=-7

"Twice the second number is 10" => 2y=10

So we have three equations:

x+y+z=6

x-y=-7

2y=10

Then we want to solve the system by solving for the variables one by one starting with "y" since we can directly solve for it.

2y=10 => y=10/2 => y=5

Then plug y=5 into the second equation to solve for x.

x-(5)=-7 => x=-2

Lastly, substitute both x and y back into the top equation to solve for z. Which i will leave to you :)