Random sample of math scores assumed to be $\displaystyle N(\mu_{x},\sigma^{2})$: X1=644, X2=493, X3=532, X4=462, X5=565

Random sample of verbal scores assumed to be $\displaystyle N(\mu_{y},\sigma^{2})$: Y1=623, Y2=472, Y3=492, Y4=661, Y5=540, Y6=502, Y7=549, Y8=518

How do I find a 90% confidence level for $\displaystyle \mu_{x}-\mu_{y}$?