1. The problem asks to write the numbers $7.²$ and $21.2⁴$ in the form $\frac{a}{b}$ where $b \neq 0$. 2. First, interpret the notation: $7.²$ means $7.2$ (7 point 2) and $21.2⁴$ means $21.24$ (21 point 24). 3. To convert a decimal to a fraction, write the decimal number as $\frac{\text{integer without decimal}}{10^{\text{number of decimal places}}}$. 4. For $7.2$, there is 1 decimal place, so: $$7.2 = \frac{72}{10}$$ 5. Simplify $\frac{72}{10}$ by dividing numerator and denominator by 2: $$\frac{72}{10} = \frac{36}{5}$$ 6. For $21.24$, there are 2 decimal places, so: $$21.24 = \frac{2124}{100}$$ 7. Simplify $\frac{2124}{100}$ by dividing numerator and denominator by 4: $$\frac{2124}{100} = \frac{531}{25}$$ 8. Final answers: - $7.2 = \frac{36}{5}$ - $21.24 = \frac{531}{25}$