The first term of an arithmetic sequence is - 3 and the fifteenth term is 53. What is the common difference of the sequence?

T15=a + (n-1) d where: "T15" is the 15th term, "a" is the 1st term, "n" is the number of terms and "d" is the common diff. Thus; 53=-3 + (15-1) d 53=-3+14d 53+3=14d 56=14d d=56/14 d=4