## Key Concepts

- Model problems using equations, drawings and arrays

## Equation

First, find the equation of an array and add them row-wise or column-wise**.**

**Example:**

Write the equation for the given array.

**Solution:**

Here, there are 2 rows and 3 columns.

So, the row-wise equation of the image is 3 + 3 = 6.

There are 6 pumpkins present in the image.

### Drawing

Draw the image of the array and solve the problem.

**Example:**

Rachel ate 3 slices of pizza each day. Write how many slices of pizza she ate at the end of 3^{rd} day. Draw the array and find the answer.

**Solution:**

She ate 3 slices of pizza on day 1.

On the 2^{nd} day, she ate 3 slices of pizza.

On the 3^{rd} day, she ate 3 slices of pizza.

So, at the end of the 3rd day, she ate 3 + 3 + 3 = 9 slices of pizza.

Therefore, Rachel ate 9 slices of pizza in total.

**Example:**

Hal arranged the leaves into 3 rows and 3 columns. How many leaves does Hal have in all?

**Solution:**

Here, there are 3 rows and 3 columns.

So, the equation of the image is 3 + 3 + 3 = 9.

There are 9 leaves present in the image.

**Example:**

Mindy draws 5 rows of stars in her notebook. In each row, she placed 5 columns of stars. So, how many stars does she draws?

**Solution:**

Here, there are 5 rows and 5 columns.

So, the equation of the image is 5 + 5 + 5 + 5 + 5 = 25.

There are 25 stars present in the image.

**Example:**

Nill has a collection of sunglasses. He placed those in 3 rows and 3 columns. So, how many sunglasses does he have in total?

**Solution:**

Here, there are 3 rows and 3 columns.

So, the equation of the image is, 3 + 3 + 3 = 9.

## Exercise

- 2 rows of apples. 3 apples in each row. How many apples?
- 2 rows of cars. 4 cars per row. How many cars?
- Write two equations which explain the array.

- Write the equation by rows for the array.

- Write the equation by columns for the array.

- Jolene puts cakes out on the table. She puts 3 rows of cakes with 4 in each row on the table. How many cakes does she have in all?
- Write two equations which explains the array.

- Write the equation by columns for the array.

- Write two equations which explains the array.

- Larry puts cupcakes on a plate. He puts 2 rows of cupcakes with 5 in each row. How many cupcakes does

### What we have learned

- How to solve problems by using equations, drawings and arrays?

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