1. The problem is to understand the decimal 0.90 and its equivalent fraction form. 2. We know that decimals can be converted to fractions by considering the place value. Here, 0.90 means 90 hundredths. 3. The fraction form is therefore $\frac{90}{100}$. 4. To simplify $\frac{90}{100}$, find the greatest common divisor (GCD) of 90 and 100, which is 10. 5. Divide numerator and denominator by 10: $$\frac{\cancel{90}^{9}}{\cancel{100}^{10}} = \frac{9}{10}$$ 6. So, 0.90 is equivalent to the simplified fraction $\frac{9}{10}$. 7. The decimal 0.90, the fraction $\frac{90}{100}$, and the simplified fraction $\frac{9}{10}$ all represent the same value. 8. The 10x10 grid with 90 shaded squares visually represents $\frac{90}{100}$ or 0.90. Final answer: 0.90 = $\frac{90}{100}$ = $\frac{9}{10}$