The formula for finding area of a circle is

.
Essentially, we have two circles here. One is a larger outer circle, and the other in a smaller inner circle. In order to find the area of the sidewalk, we must find the area of the outer circle, then find the are of the inner circle. After we find both areas, we subtract.
See attached image for process of finding area, and subtracting areas to find the final area of the sidewalk.
Answer:
-16
Step-by-step explanation:
b) -x²; x = -4
-(-4)²
-(16)
-16
I hope this helps!
Answer:
Step-by-step explanation:
let s be speed and t be time taken
s*t=649
(s+8)(t-4)=649
st-4s+8t-32=649
-4s+8t-32=0
4s=8t-32
s=2t-8
2t=s+8
t=4+s/2

Part A
1. 14k+k<30
Add the left hand side to get;
15k<30
Divide both sides by 15.

k<2
2. We have 9d-3d+7>31
Group similar terms to obtain:
9d-3d>31-7
Combine similar terms:
6d>24
Divide both sides by 6

This implies that:
d>4
3. We have 13x-2x>77
This implies:
11x>77
x>7
4. We have 5y<7y+18
This implies
5y-7y<18
-2y<18
Divide both sides by -2 and reverse the sign.


5. The given expression is;
3f-12>-10+9f
Group similar terms:
-12+10>9f-3f
-2>6f
Divide both sides by 6.



6. We have 4t-8<2t-2
Group similar terms;
4t-2t<-2+8
2t<6
t<3
7. We have
15h+16>6h-20
Group like terms;
15h-6h>-20-16
9h>-36
Divide both sides by 9
h>-4
8. The given inequality is
4r-2r>6-r
This implies
4r-2r+r>6
3r>6
r>2
Part B
x-27=193
x=193+27
x=220
2. The given equation is
f(12)=48
or
12f=48
f=48/12
f=4
3. We have the equation 4s+2=74
4s=74-2
4s=72
s=18
4. The given equation is
9(r+1)-18=2r+12
Expand to get:
9r+9-18=2r+12
Group like terms:
9r-2r=12+18-9
7r=21
r=3