Answer:
225
Step-by-step explanation:
The sum of this series is given by the formula:
![S_n=\frac{n}{2}[2a+(n-1)d]](https://tex.z-dn.net/?f=S_n%3D%5Cfrac%7Bn%7D%7B2%7D%5B2a%2B%28n-1%29d%5D)
Where
S_n is the sum
a is the first term (we get this by plugging in n = 1 into "2n-1", we have 2(1) - 1 = 1)
n is the number of terms (the sum is defined for n = 1 to n = 15, so 15 terms)
d is the common different (the difference is successive terms. Here, 2nd term would be 2(2) - 1 = 3, and first term was 1, so d = 3 -1 = 2)
<em>plugging in the info, we will get the sum:</em>
<em>
</em>
<em>The sum is 225</em>
Answer:
b=-25
Step-by-step explanation:
10= -2/5b
10= -2/5b
------ -------
-2/5 -2/5b
b=-25
Check:
-2/5(-25)=10
10=10
25 dollars per hour should be the correct answer
80% is the same as 4/5, so 4/5 of the class= 20. That means that if there was a picture, 4 parts would be shaded, and 1 would not. 1/4 of 20 is 5, so 1 part= 5 people. 5 x 5 = 25. 25 is the answer. :)