Question

In a parallelogram , one angle is $\frac{4}{5}$^th of its adjacent angle. Then the angles of the parallelogram are

• A. 60, 75
• B. 100, 80
• C. 48, 60
• D. 80, 64

Answer 1

The correct option is B

100, 80

Let $x$ and $y$ be the adjacent angles of the parallelogram.

Then, $x+y=180$ ...(1)

And, $x=\frac{4}{5}y$

$5x=4y\Rightarrow 5x-4y=0$ ...(2)

Multiplying (1) by 4,

$4x+4y=720$ ...(3)

Adding (2) and (3),

$9x=720\Rightarrow x=80$

$\therefore y=180-80=100$

Therefore, the angles are ${100}^0$,${80}^0$.