1, Xiaoming has 15 apples. He ate five and bought 10 apples. How many apples does he have now? The rectangle is 8 cm long and 6 cm wide. What's its circumference? A car is driving at a speed of 60 kilometers per hour. How many kilometers did it travel in two hours? A piece of chocolate can be divided into 9 small pieces. Xiao Ming is divided into three small pieces. How many small chocolates does he have left?

2. The price of a book is 18 yuan, and the price of a pen is 2 yuan. How much does it cost to buy these two things? Note: this question examines the basic addition and subtraction. There were 15 apples at first. After eating five apples, there is 10 left. Then buy 10, 10+ 10=20, so Xiaoming has 20 apples now.

3, this question is the calculation of speed multiplied by time. The distance traveled by a car in two hours is 60 * 2 = 120km. This topic examines the addition and subtraction of fractions. A piece of chocolate is divided into 9 small pieces, Xiao Ming is divided into 3 small pieces, leaving 9-3=6 small pieces. This topic examines addition. The price of the book is 18 yuan, and the price of the pen is 2 yuan, so it takes 18+2=20 yuan to buy these two things.

Methods of learning mathematics

1, it is very important to know the basics. Mathematics is a progressive subject, which means that new concepts and skills are often based on old knowledge. Therefore, it is very important to ensure that you have a deep understanding and mastery of basic knowledge, such as arithmetic operations, fractions, decimals, percentages and so on. Practice is the key to improve mathematics ability.

2. Practice is the core of solving mathematical problems. Through a lot of practice, you can enhance your understanding and memory. Practice is also an effective way to exercise problem-solving skills and improve problem-solving speed. Active learning is also the key to learning mathematics well. This means that you should take an active part in class discussion and dare to ask questions. If you don't understand, you can ask for help.

3. Actively look for learning resources, such as teaching videos, online courses, reference books, etc. It can also help you to understand mathematical concepts more deeply. Apply mathematics to real life. Mathematics is not only a subject, but also a tool that can be used to understand and solve problems in real life.