## Key Concepts

Solve word problems to add and subtract values using equations

### 1. Find the unknown numbers

- We can use counters to find the missing number.
**Example:**Find the missing value in 15 – _____ = 8

### 2. True or false equations

- We can verify if a numerical equation is true.

Let us check whether the given equation is true or not.

3 + 6 = 4 + 5

**Step 1: **Find the value of each side of the equation.

**Step 2:** Compare the values on both sides of the equation.

Here, LHS = RHS

So, the given equation is true.

### 3. Equations with no operations

- Equations without any mathematical operations can also be true.

**Example: **Verify if the equation 3 = 3 is true.

**Sol: **Value at LHS is 3.

Value at RHS is also 3.

So, the equation is true.

### 4. Addition and subtraction using equations

Steve baked 35 muffins. Arthur baked 52 muffins. How many muffins did Steve bake less than Arthur?

**Step 1:** Make sense

Understand the problem given to find the missing value and place the given values in a table.

**Step 2:** You can write an addition or subtraction equation to find the missing value.

52 = _____ + 35

or

52 – 35 = ______

Therefore, Arthur made 17 muffins more than Steve.

## Exercise

- James has 5 books. His mother gifts him 3 more books on his birthday. How many books does James have now?
- Tony and Chris together bake 15 cakes. If Tony alone baked 8 cakes, how many cakes did Chris bake?
- Amy has 11 more pencils than Rachel. If Rachel has 6 pencils, how many pencils does Amy has?
- Neo has 24 toys. He gave 12 toys to his sister. How many toys does he have now?
- Jen buys 5 sunflower plants and 8 tulip plants. How many plants did Jen buy in total?
- Christ wants to visit 13 states. He already visited 9 states. How many states does he need to cover more?
- Tom and Dennis scored 54 runs together in cricket. If Tom scored 28, what was Dennis’s score?
- Mother gave 4 chocolates to Alex. Later, his grandfather gave 5 chocolates to Alex. How many chocolates does he have in total?
- Tina had $37.50. She bought a book for $9.30 and had lunch for $12.15. How much money is left with her?

### Concept Map :

### What we have learned

- We can use addition or subtraction to find the missing numbers.

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