Answer:
[tex]\large\boxed{1.\overline{21}=\dfrac{40}{33}}[/tex]
Step-by-step explanation:
[tex]x=1.\overline{21}\\\\x=1.212121...\qquad\text{multiply both sides by 100}\\\\100x=121.212121...\\\\\text{subtract x from 100x}\\\\100x-x=121.212121...-1.212121...\\\\99x=120\qquad\text{divide both sides by 99}\\\\x=\dfrac{120}{99}\\\\x=\dfrac{120:3}{99:3}\\\\x=\dfrac{40}{33}[/tex]
