Answer 420.
a, is the first term. d is difference.
Since this is an arithmetic progression, I use this formula.
Un = nth term
Sn = sum of terms.
First find the number of terms, which is 20.
Then use the second formula to find the sum.
Answer:
You are definitely correct! It is 81w^2.
Step-by-step explanation:
Since x is 12, you add that with 3 so you get 15, then multiply it by 2 which you get 30
-3x=48 ---> x=-16
5x-1=29 --> x=6
4(x-6)+7=23 --> x=10
3(x-4)+5x=4 --> x=2