Solve for in the equation
For one-variable linear equations like , first use the distributive property to remove parentheses, then use inverse operations in reverse order of operations: undo addition or subtraction to isolate the term with the variable, then undo multiplication or division to solve for the variable. Quickly check your answer by substituting it back into the original equation to see if both sides match.
Hints
Look at the structure
Notice that the left side has a number multiplying a parenthesis. What property lets you remove the parentheses?
Simplify the left side first
Write without parentheses by multiplying 3 by both and .
Isolate the variable step by step
After you expand, you will have an equation like . What operation will move the to the other side? After that, how do you get alone?
Desmos Guide
Graph both sides of the equation
In Desmos, enter y = 3(x - 4) on one line and y = 15 on another line to represent both sides of the equation as functions.
Find the intersection
Look for the point where the two graphs intersect and tap/click it; read off the x-coordinate of that intersection point—that x-value is the solution to the equation.
Step-by-step Explanation
Apply the distributive property
Start by expanding the left side of the equation.
Multiply 3 by each term inside the parentheses:
Undo the subtraction to isolate the term
Now get by itself. The equation is:
Add 12 to both sides to keep the equation balanced:
Solve for
Now isolate by undoing the multiplication by 3. Divide both sides by 3:
So the solution is , which corresponds to choice D.