Answer:
D. 5
Step-by-step explanation:
We have been given a parallelogram CDEF and we are asked to find the value of r.
Since the opposite sides of parallelogram are equal, so we can equate length of side CF by DE.
Using our given information we will come with an equation as:
[tex]10r-20=6r[/tex]
Let us add 20 to both sides of our equation.
[tex]10r-20+20=6r+20[/tex]
[tex]10r=6r+20[/tex]
Let us subtract 6r from both sides of our equation.
[tex]10r-6r=6r-6r+20[/tex]
[tex]4r=20[/tex]
Upon dividing both sides of our equation by 4 we will get,
[tex]\frac{4r}{4}=\frac{20}{4}[/tex]
[tex]r=5[/tex]
Therefore, the value of r is 5 and option D is the correct choice.
