knitr::include_graphics('Capture.png')

# Create matrix for W and B
W = matrix(c(1,2,-1,1,1,0,3,1,2,1,1,2), 4,3) 
B = matrix(c(1,1,0,1), 4,1)

# Merge both matrix into df

data <- cbind(W,B)

# Load the library

library(pracma)

# Calculate RREF using R's function

rref(data)
##      [,1] [,2] [,3]      [,4]
## [1,]    1    0    0 0.3333333
## [2,]    0    1    0 0.0000000
## [3,]    0    0    1 0.3333333
## [4,]    0    0    0 0.0000000

The above is in the subspace of W because of non-zero value