n1<-12
n2<-8
x_bar<-65
y_bar<-48
sx_2<-279
sy_2<-224

sp<-sqrt(((n1-1)*sx_2+(n2-1)*sy_2)/(n1+n2-2))


t<-qt(0.975,n1+n2-2)#with 0.975 and 18 df


CL1<-(x_bar-y_bar)-t*sp*sqrt(1/n1+1/n2) #lower 95% CI
CL1

#1.608831

CL2<-(x_bar-y_bar)+t*sp*sqrt(1/n1+1/n2) #higher 95% CI
CL2

# 32.39117