Lucy bought a doormat for $7 and some placemats for $2 each. Her total average cost per item was $3. Create a rational equation, and determine how many placemats she bought.

She bought

placemats.

(2x+7) / (x+1) = 3; Relation

Lucy bought 4 place-mats

Step-by-step explanation:

Let the number of place-mats bought by Lucy be equal to x. The total cost of these x place-mats, at $2 each, would be;

2x

Her total cost will then be;

2x + 7; since she bought one doormat at $7.

The total items bought by her is then equal to;

x + 1

Her total average cost can thus be given as;

total cost / total number of items

(2x+7) / (x+1)

Therefore, we can formulate the following relation;

(2x+7) / (x+1) = 3; since the average cost per item was $3

2x+7 = 3 (x+1)

2x+7 = 3x + 3

7-3 = 3x-2x

4 = x

Therefore, Lucy bought 4 place-mats