Question

The sum of all five terms of an arithmetic sequence is $55$. Find the sum of the first three terms of the sequence if the sum of the last three is $48$.

Answer 1

18

Step-by-step explanation:

The first step is to calculate the third term

= 55/5

= 11

The next step is to calculate the sun of last two terms

= sum of last three terms-third term

= 48-11

= 37

Therefore the sum of the first three terms can be calculated as follows

= 55-37

= 18

Hence the sum of the first three terms is 18