Equivalent equations are equations that have the same value
The equation in logarithmic form is 
<h3>How to rewrite the equation</h3>
The expression is given as:

Take the logarithm of both sides

Apply the power rule of logarithm

Divide both sides by log(10)

Apply change of base rule

Divide both sides by 2

Rewrite as:

Hence, the equation in logarithmic form is 
Read more about logarithms at:
brainly.com/question/25710806
The equation for a circle is (x - h)^2 + (y - k)^2 = r^2
where (h, k) is the center and r is the radius
(x + 8)^2 + (y + 9)^2 = 169
Since the equation is -h and -k, I will rewrite in terms of -h and -k.
(x - -8)^2 + (y - -9)^2 = 13^2
The center is (-8, -9) and the radius = 13
Let me know if you need me to explain further.
Pythagoras theorem I guess
6. One variable only so pretty straightforward.
length-x+4
width-x
x+x+4=80
2x=76
x=38
x+4=42
answer: length 42cm and width 38cm
7. Another money problem!
n-# of nickels
q-# of quarters
n=3+q
0.05n+0.25q=2.85
Substitution works like a charm!
0.05(3+q)+0.25q=2.85
0.15+0.05q+0.25q=2.85
0.3q=2.7
q=9
n=3+q
n=3+9
n=12
answer: 9 nickels and 12 quarters
8. One variable situation again.
Ann's money-2b+9
Betty's money-b
b+2b+9=60
3b=51
b=17
2b+9=43
answer: Ann has $43 and Betty has $17.
9. # of red m&m's-x+1
# of blue m&m's-x
x+1+x=13
x=6
x+1=7
answer: 6 blue and 7 red m&m's
10. a-number of adult tickets
s-number of student tickets
a+s=785 ----> a=785-s
5a+2s=3280
5(785-s)+2s=3280
-3s=-645
s=215
a+s=785
a+215=785
a=570
answer: 215 children tickets and 570 adult tickets