The number of terms n is 7.
<u>Explanation:</u>
Given that:
First term a=21
nth term 
=39
Sum up to n terms 
=210
To Find:
The number of terms n in the arithmetic progression.
Formula to be used:
Sum up to n terms Sn is given by the expression
Solution:
Number of terms n in the given series is n=7
Answer:Biodiversity boosts ecosystem productivity where each species, no matter how small, has an important role to play. For example, A larger number of plant species means a greater variety of crops. Greater species diversity ensures natural sustainability for all forms of life.
Explanation:
The US proved that it had the industrial strength and man power to become a world power
in the emperors capital if i'm correct it is Kyoto or Tokyo
