Find the recursive formula the explicit formula in the indicated term for each arithmetic sequence
a.) 7 , 11 , 15, . . . 7th term
b.) -7 , -5, -3, . . . 23rd term
c.) 18,11, . . . 6th term
d.) 3, 3.5, 4, . . . 16th term 
Answer in this format
ASAP (will give brainliest)
20 points
