Math 2 Lesson: Find the number minus

### 1.1. Knowledge to remember

### 1.2. Math forms

**Form 1: Find x**

– To find the minus number, we subtract the difference from the subtracted number.

– To find the number to be subtracted, we take the difference plus the minus number.

**Form 2: Complete the table**

Fill in the missing subtraction, subtraction or difference values in the table.

– Find the difference by subtracting two numbers: Subtracted and Subtracted numbers.

– Find the number to be subtracted or subtracted (Form 1)

**Form 3: Math Quiz**

– Read and analyze the problem: The problem usually gives the initial value and the remaining value, requires finding the value that has been reduced or decreased.

– Find the solution of the problem: To find the reduced value, we usually take the original value minus the remaining value.

– Presentation of the problem.

– Check the solution and the results you just found.

### 1.3. Solving Textbook Exercises

**Lesson 1**

Find x:

a) \(x – 4 = 8\); b) \(x – 9 = 18\); c) \(x – 10 = 25\)

d) \(x – 8 = 24\); e) \(x – 7 = 21\); g)\(x – 12 = 36\).

__Solution method__

– To find the minus number, we subtract the difference from the subtracted number.

– To find the number to be subtracted we take the difference of addition and subtraction.

__Solution guide__

a) \(x – 4 = 8\)

\(x = 8 + 4\)

\(x = 12\)

b) \(x – 9 = 18\)

\(x = 18 + 9\)

\(x = 27\)

c) \(x – 10 = 25\)

\(x= 25 + 10\)

\(x = 35\)

d) \(x – 8 = 24\)

\(x=24+8\)

\(x = 32\)

e) \(x – 7 = 21\)

\(x = 21 + 7\)

\(x = 28\)

g) \(x – 12 = 36\)

\(x = 36 + 12\)

\(x = 48\)

**Lesson 2**

Write the correct number in the blank:

__Solution method__

– To find the difference, we subtract the minus number from the subtracted number.

– To find the minus number, we subtract the difference from the subtracted number.

– To find the number to be subtracted we take the difference of addition and subtraction.

__Solution guide__

**lesson 3**

A bus station has 35 cars, after some cars leave the station, there are 10 cars left in the station. How many cars have left the station?

__Solution method__

To find how many cars have left the station, we subtract the number of cars from the original station in the station.

__Solution guide__

The number of cars leaving the station is:

35 – 10 = 25 (car)

Answer: 25 cars.

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