in a sample with M 40 and s 8 what is the z score correspond

in a sample with M= 40 and s= 8, what is the z score corresponding to X=38?

1- 0.25 2- 0.50 3- -0.25 4- -0.50

Thank you to whoever helps me out!

Mean ( u ) =40
Standard Deviation ( sd )=8
Normal Distribution = Z = X- u / sd ~ N(0,1)
Z = (38-40)/8
Z = -2/8 = -0.25