supplementary angles add up to 180°.
x = measure of such angle
x + 20 = measure of her sibling.
since "x" has 20 less than her sibling, then clearly her sibling has to have 20 more than "x".

Answer:

Step-by-step explanation:
We know that the length is four times the width, so:

We also know the area, which is 324 m². The formula for area:

Insert the known values:

Solve for w. Simplify by removing parentheses:

Divide 4 from both sides to isolate the variable:

Find the square root of both sides:

The width is 9 m.
We know the width. Now find the length by using the area formula and inserting known values:

Solve for l. Divide both sides by 9:

The length of the rectangle is 36. (You can check: 4 times 9 is 36)
Now find the perimeter:

Insert values:

The perimeter is 90 m.
given: 
$\therefore Ac=\frac{(2)2}{2}=2$
The original number would be 900
Answer:
24
Step-by-step explanation:
Let x be the points he scored in his best game. x-8 would then represent each of his last 3 games.
(x-8)*3 = 2x
3x-24=2x
x=24