Answer:
Elsa's error was adding (4r+r) instead of subtracting (4r-r)
Step-by-step explanation:
we have
[tex](3b+4r)+ (-2b-r)[/tex]
step 1
Eliminate the parenthesis
[tex]3b+4r-2b-r[/tex]
step 2
Group terms that contain the same variable
[tex]3b-2b+4r-r[/tex]
step 3
Combine like terms
[tex]b+3r[/tex]
therefore
Elsa's error was adding (4r+r) instead of subtracting (4r-r)
