Answer:
is proved for the sum of pth, qth and rth terms of an arithmetic progression are a, b,and c respectively.
Step-by-step explanation:
Given that the sum of pth, qth and rth terms of an arithmetic progression are a, b and c respectively.
First term of given arithmetic progression is A
and common difference is D
ie.,
and common difference=D
The nth term can be written as

pth term of given arithmetic progression is a

qth term of given arithmetic progression is b
and
rth term of given arithmetic progression is c

We have to prove that

Now to prove LHS=RHS
Now take LHS




![=\frac{[Aq+pqD-Dq-Ar-prD+rD]\times qr+[Ar+rqD-Dr-Ap-pqD+pD]\times pr+[Ap+prD-Dp-Aq-qrD+qD]\times pq}{pqr}](https://tex.z-dn.net/?f=%3D%5Cfrac%7B%5BAq%2BpqD-Dq-Ar-prD%2BrD%5D%5Ctimes%20qr%2B%5BAr%2BrqD-Dr-Ap-pqD%2BpD%5D%5Ctimes%20pr%2B%5BAp%2BprD-Dp-Aq-qrD%2BqD%5D%5Ctimes%20pq%7D%7Bpqr%7D)




ie., 
Therefore
ie.,
Hence proved
Hello There!
<u><em>n - d = 0</em></u>
<u><em>5n+10d = 90</em></u>
<u><em>----------------------</em></u>
<u><em>n-d = 0</em></u>
<u><em>n+2d = 18</em></u>
<u><em>-------------------</em></u>
<u><em>Subtract and solve for "d":</em></u>
<u><em>3d = 18</em></u>
<u><em>d = 6 (# of dimes)</em></u>
<u><em>n = d = 6 (# of nickels)</em></u>
Distribute first.
.75 times 8 + .75 times e, which is 6+.75e = 2-1.25e
Then subtract 2 from both sides,
4+.75n=-1.25e
Next subtract .75 from both sides,
4=-2e
Divide both sides by -2, and you will get e= -2. Hope this helps!
Im assuming you mean 20pence? if so its 5 twenty pence in a pound so times 5 by 9 gives you 45
so there are 45 twenty pence in £9