g is a linear function such that

g(1)=7.5 and g(7)=12.6
Find the formula for g(x).

I've tried doing it and the formula i got was:
y = 0.9x + 6.6
is that correct?

I got the slope to be .85

then y = .85x + b
plug in (1,7.5)
7.5 = .85 + b
b = 6.65

my equation is
y = .85x + 6.65

both given points satisfy my equation exactly, your don't