Answer:
975
Step-by-step explanation:
There are two ways you can solve this. First, you can write down all of the numbers and add it all together.
30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
Another way to do it is to plug it into a formula.
First, you have to find the first and last number of the sequence. The problem gives you the first number (30) so you plug the number into the arithmetic sequence formula for the last one
a{n}=a{1}+(n-1)d
an is the term you are looking for in the sequence
a1 is the first term in the sequence
d is the difference between the terms
a15=30+(15-1)5
a15=100
The first and last number are 30 and 100
Plug it into the formula
Sn=n((a1+an)/2)
Sn is going to be the total sum
n is the number of terms
a1 is the first term
an is the last term
Sn = 15((30+100)/2)
Sn=15*65
Sn= 975
