Question

figure cdef is a parallelogram. what is the value of r? 2 3 4 5

Explanation:

Step1: Set equal opposite sides

In a parallelogram, opposite sides are congruent. So we set $10r - 20 = 6r$.

Step2: Solve for $r$

Subtract $6r$ from both sides:
$10r - 6r - 20 = 0$
$4r - 20 = 0$
Add 20 to both sides:
$4r = 20$
Divide by 4:
$r = \frac{20}{4} = 5$
We can verify with the other pair of sides: substitute $r=5$ into $2r+12$ gives $2(5)+12=22$, and the opposite side (not labeled, but consistency holds as our first equation is valid for parallelogram properties).

Answer:

5