Answer :

[tex]16a+5=21a\\ 5a=5\\ a=1[/tex]
[tex]16a+5=21a\\\\21a=16a+5\ \ \ \ \ |subtract\ 16a\ from\ both\ sides\\\\5a=5\ \ \ \ |divide\ both\ sides\ by\ 5\\\\\boxed{\boxed{a=1}}[/tex]

Other Questions