If , what is the value of ?
For one-step linear equations like , focus on isolating the variable by using the inverse (opposite) operation on both sides of the equation. Identify what is being done to (subtracting 7), then do the opposite (add 7) to both sides to keep the equation balanced. Perform the arithmetic carefully and, if you have time, plug your result back into the original equation to confirm it makes the statement true.
Hints
Identify the operation on x
Look at how is being changed in . What operation is being done to ?
Use the opposite operation
To undo subtracting 7 from , think about which operation will cancel the if you do it to both sides of the equation.
Keep the equation balanced
Whatever you do to the left side of the equation, you must also do to the right side. After you cancel the , simplify the number on the right.
Desmos Guide
Enter the related graphs
In Desmos, type y = x - 7 on one line and y = 12 on the next line. You will see a slanted line and a horizontal line.
Find the intersection point
Click where the two lines intersect. Desmos will display the coordinates of this point.
Read the solution for x
Look at the x-coordinate of the intersection point; that value is the solution to . Choose the answer choice that matches this x-value.
Step-by-step Explanation
Understand the equation
The equation means that when 7 is subtracted from some number , the result is 12.
To find , we need to undo the subtraction of 7.
Use the inverse operation to isolate x
The inverse (opposite) of subtracting 7 is adding 7.
Add 7 to both sides of the equation to keep it balanced:
On the left side, and cancel, leaving just .
Simplify to find the value of x
Now simplify the right side:
So the equation becomes .
This matches answer choice C, so the correct answer is 19.