To place an ad in a newspaper, it costs plus for each line.

Write the expression.

Phrase: Sum of and for eachline.

Expressions: .

Find the cost for an ad that has lines.

Substitute the cost of lines in the expression and simplify.

First operation is multiplication.

                (Multiply: )

Next operation is addition.

                    (Addition: )

Thus, the cost of lines is .

Make a table showing the cost if there are and lines in the ad.

Number of lines	Expression	Cost of lines
	\ \
	\ \	\ \
	\ \	\ \
	\ \	\ \

Observe the table:

Look for a pattern in the costs.

As the number of lines incresed by , the cost increases by .

The cost of lines is .