Question

The 20th term of an arithmetic sequence is 27 and the first term is -11. What is the common difference??

Answer 1

using the standard notation:

term(20) = a + 19d = 27
and
a = -11

-11 + 19d = 27
19d = 38
d = 2

the common difference is 2

check:
term(2) = a+19d
=-11 + 19(2)
= -11+38
= 27