1) Calculate the area of the original rectangle: 15 * 7 = 105.
2) Calculate the area of the rectangles into which you want to divide the original: 3 * 5 = 15.
3) Divide the resulting areas: 105/15 = 7.
Conclusion: since the division received an integer, it means that the 15×7 rectangle can be divided into 3×5 rectangles and their number will be 7.
One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.