Solving simultaneous equations with R

Question

Suppose I have the following equations:

 x + 2y + 3z = 20  
2x + 5y + 9z = 100  
5x + 7y + 8z = 200

How do I solve these equations for

Answer 1

For clarity, I modified the way the matrices were constructed in the previous answer.

a <- rbind(c(1, 2, 3), 
           c(2, 5, 9), 
           c(5, 7, 8))
b <- c(20, 100, 200)
solve(a, b)

In case we need to display fractions:

library(MASS)
fractions(solve(a, b))