Question

properties of parallelograms
solve for the unknown
variable (x).
answer: round to whatever you
see in the problem.

Explanation:

Step1: Use the property of parallelograms

In a parallelogram, consecutive angles are supplementary. So, $\angle F+\angle D = 180^{\circ}$.

Step2: Set up the equation

We know that $\angle F=(2x + 18)^{\circ}$ and $\angle D = 40^{\circ}$. Then, $(2x+18)+40=180$.

Step3: Simplify the equation

$2x+58 = 180$.

Step4: Solve for $x$

Subtract $58$ from both sides: $2x=180 - 58=122$. Then divide by $2$: $x=\frac{122}{2}=11$.

Answer:

$11$