sequences and theries help (1 Viewer)

[noobs]

6 hours of study leads to some sort of brain block...

Find the first term and the common difference of an arithmetic sequence whose fifth term is 31 and 12th term is 73.
so i know
t5=a+4d=31
t12=a +11d=73...
the answers just say first terms 7 and common dif is 6 why?

 

[Trebla]

Solve simultaneously for a and d and you're done....