A+b+c=180
subsittute
x+25+x-5+c=180
2x+20+c=180
minus 20 both sides
2x+c=160
mius 2x
c=160-2x
We need to know some log properties
1. when the base is not stated, assume that it is base 10 or log₁₀
2.

-log(10^-1)=

answer is D. -1
Answer:
Percent Decrease = 20% Decrease
Step-by-step explanation:
To find percentage decrease, we will use a simple formula shown below:
Percentage Decrease/Increase = 
Where
New is the latest number of members (which is 24)
Old is the initial number of members (which is 30)
<em>Note: the multiplication by a factor of "100" brings the answer to a percentage</em>.
Now, lets substitute the numbers and figure out the percentage decrease:

So, it comes to -20, which is a decrease of 20%