find the sum of the 20 terms of 5+10+15
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Answer:
Sn = n/2(2a+(n-1)d)
n=20, d= 10-5=5, a=5
S20= 10(10+19×5)
= 10(95+10)
=10×105
=1050
S20 = 1050
hope it helps.....
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