Answer:
r = 6
Step-by-step explanation:
To get the value of r we will use the pythagoras theorem a shown;
PR² = QR² + PQ²
(4+r)² = 8² + r²
Expand
16+8r+r² = 64 + r²
16 + 8r = 64
8r = 64 - 16
8r = 48
r = 48/8
r = 6
Hence the value of r is 6
Between 4 and 6 is where u put the grouping symbols!
Well I need more details for x can you screenshot? It’s usually x*0.20 but I need more details to help you
Let
y-------> number of books read during the month 
x------> number of picture of a book
we know that
in this problem
for 
calculate y
therefore
the answer is
The number of books read during the month is 
The sum of the interior angles of a polygon is (n-2)*180, n being the number of sides.
a nonagon has nine sides, so the total of interior angles is (9-2)*180=7*180
this is a regular nonagon, so each interior angle has the same degrees:
7*180/9=7*20=140
the exterior angle=180-the interior angle=180-140=40
40 is the correct answer.
