B3. Solve the equation $4 \cdot 25^{x} + 5 \cdot 16^{x} = 9 \cdot 20^{x}$.

## 22nd Mathematics Knowledge Competition for Students of Secondary Technical and Vocational Schools National Competition, April 23, 2022

## Problems for 4th Year

Time for solving: 120 minutes. In section A, we will award three points for each correct answer, and deduct one point for each incorrect answer. Write your answers for section A in the left table, leave the right table blank.
![](https://cdn.mathpix.com/cropped/2024_06_07_37ea02f5a530d200baf4g-14.jpg?height=168&width=804&top_left_y=590&top_left_x=638)