Question

For what value of p are 2p+1,13,5p-3 three consecutive terms of an ap

Answer 1

13-(2p+1)=5p-3-(13)
from there
p=4

Answer 2

we know that, AM=(a+b)/2
AM=13, a=2p+1, b=5p-3
therefore,...
13=[2p+1+5p-3]/2
13×2=7p-2
26=7p-2
7p=26+2
7p=28
p=4
.. hope it helps you..