634, you have to multiply it by 89% of the original number, 712, to deduct 11%
10. It is basically 2/3 of 15. 15/3=5 5*2=10
Bksnsskbd fcnfkdn sishfmdibaub subneibfs uh a
Now, we know the 4th term is 5.... ok... now, what's the
common difference? well, we dunno, but notice, from the 4th to the 13th term, you do have to use it 9 times to hop over to the 13th term, let's say is "d", then
![\bf \begin{array}{llll} term&value\\ ------&------\\ a_4&5\\ a_5&5+d\\ a_6&(5+d)+d\\ a_7&(5+d+d)+d\\ a_8&(5+d+d+d)+d\\ a_9&(5+d+d+d+d)+d\\ a_{10}&(5+d+d+d+d+d)+d\\ a_{11}&(5+d+d+d+d+d+d)+d\\ a_{12}&(5+d+d+d+d+d+d+d)+d\\ a_{13}&(5+d+d+d+d+d+d+d+d)+d\\ &5+9d \end{array}](https://tex.z-dn.net/?f=%5Cbf%20%5Cbegin%7Barray%7D%7Bllll%7D%0Aterm%26value%5C%5C%0A------%26------%5C%5C%0Aa_4%265%5C%5C%0Aa_5%265%2Bd%5C%5C%0Aa_6%26%285%2Bd%29%2Bd%5C%5C%0Aa_7%26%285%2Bd%2Bd%29%2Bd%5C%5C%0Aa_8%26%285%2Bd%2Bd%2Bd%29%2Bd%5C%5C%0Aa_9%26%285%2Bd%2Bd%2Bd%2Bd%29%2Bd%5C%5C%0Aa_%7B10%7D%26%285%2Bd%2Bd%2Bd%2Bd%2Bd%29%2Bd%5C%5C%0Aa_%7B11%7D%26%285%2Bd%2Bd%2Bd%2Bd%2Bd%2Bd%29%2Bd%5C%5C%0Aa_%7B12%7D%26%285%2Bd%2Bd%2Bd%2Bd%2Bd%2Bd%2Bd%29%2Bd%5C%5C%0Aa_%7B13%7D%26%285%2Bd%2Bd%2Bd%2Bd%2Bd%2Bd%2Bd%2Bd%29%2Bd%5C%5C%0A%265%2B9d%0A%5Cend%7Barray%7D)
we also know that the 13th term is -1
![\bf \stackrel{a_{13}}{5+9d}=-1\implies 9d=-6\implies d=\cfrac{-6}{9}\implies \boxed{d=-\cfrac{2}{3}}](https://tex.z-dn.net/?f=%5Cbf%20%5Cstackrel%7Ba_%7B13%7D%7D%7B5%2B9d%7D%3D-1%5Cimplies%209d%3D-6%5Cimplies%20d%3D%5Ccfrac%7B-6%7D%7B9%7D%5Cimplies%20%5Cboxed%7Bd%3D-%5Ccfrac%7B2%7D%7B3%7D%7D)
now, recall above what the 8th term is
The goal is to get 'p' by itself. (I am assuming that the problem is (p+2)-4=14)
1. add 4 to both sides
2. subtract 2 on both sides
3. you have your answer