Question: use relevant formulae working algebra and logical reasoning...

Use relevant formulae , working , algebra and logical reasoning. Please do not attempt any trial and error methods or writing out the values individually 

A challenge was set in class after learning about sequences, which group could create a question that many of their class mates would find difficult to solve. 
Group A's question won the challenge so here it is for you to solve: 

If you add the 1st term and the 17th term of an Arithmetic Progrssion, the answer will be 40 

the following subtraction (10th-5th term) of the same Arithmetic Progression, the answer will be 15 

find the values of the first term and the common difference of the arithmetic sequence