If the 4th term of an arithmetic sequence is 24 and the 12th term is 56, whats the first term?

2 answers

done
http://www.jiskha.com/display.cgi?id=1467199616

why are you switching names?
a+11d=56---->1
a+3d=24----->2
1-2 we get
8d=32
d=4
put d=4 in 2
a+3(4)=24
a+12=24
a=24-14
a=10