we know that
The general equation for an aritmetic sequence is equal to
an=a1+d(n-1)
where
a1 is the first term
d is the common difference
In this problem we have
a9=-7
d=-9
so
For n=9
we have
-7=a1+(-9)(9-1)
-7=a1-72
a1=72-7
a1=65
Find a2
a2=a1+d
a2=65+(-9)
a2=56
Find a3
a3=a2+d
a3=56-9
a3=47
therefore
the first three terms of the sequence are
65,56,47