Question

The explicit rule for an arithmetic sequence is an = -4 + (n - 1)7. What is the common difference of the arithmetic sequence? d = What is the first term of the arithmetic sequence?

Answer 1

An = -4 + (n - 1)(7)
This being in the form of the explicit rule for an arithmetic sequence you can pick out the d and a1.
an = a1 + (n - 1)(d)
d = 7
a1 = -4

Answer 2

and the next thing is

x=3

y=10

z=17