> actgpa[1:5, ]
  ACT   GPA
1  30 3.992
2  25 3.377
3  20 3.009
4  24 3.509
5  32 3.969

> lactgpa = lm(GPA ~ ACT, data = actgpa)

> summary(lactgpa)

Call:
lm(formula = GPA ~ ACT, data = actgpa)

Residuals:
     Min       1Q   Median       3Q      Max 
-0.78010 -0.22341  0.05116  0.17520  0.51488 

Coefficients:
            Estimate Std. Error t value Pr(>|t|)    
(Intercept)  1.11263    0.34120   3.261  0.00331 ** 
ACT          0.08702    0.01290   6.747  5.6e-07 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 

Residual standard error: 0.2918 on 24 degrees of freedom
Multiple R-Squared: 0.6548,	Adjusted R-squared: 0.6404 
F-statistic: 45.52 on 1 and 24 DF,  p-value: 5.6e-07