load("cereal.Rdata")
lm1 <- lm(Maize ~ Barley, data = cereal)
lm2 <- lm(Maize ~ Wheat, data = cereal)
lm3 <- lm(Maize ~ Barley + Wheat, data = cereal)

lm1$coefficients

## (Intercept)      Barley 
##   -9.484660    1.085748

lm2$coefficients

## (Intercept)       Wheat 
## -30.8254882   0.9491281

lm3$coefficients

## (Intercept)      Barley       Wheat 
## -25.6646279  -0.5095537   1.3207563

summary(lm1)

## 
## Call:
## lm(formula = Maize ~ Barley, data = cereal)
## 
## Residuals:
##      Min       1Q   Median       3Q      Max 
## -106.401  -21.731   -5.482   21.282   89.921 
## 
## Coefficients:
##             Estimate Std. Error t value Pr(>|t|)    
## (Intercept)  -9.4847    32.2742  -0.294    0.772    
## Barley        1.0857     0.1919   5.657 1.88e-05 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
## Residual standard error: 45.22 on 19 degrees of freedom
## Multiple R-squared:  0.6274, Adjusted R-squared:  0.6078 
## F-statistic:    32 on 1 and 19 DF,  p-value: 1.875e-05