Marcie is putting squares onto a rectangular mat. After she finishes covering it, Marcie says the mat

measures 30 square units.

Which measurement did Marcie find?

Marcie had found the lengths were 5 units and 6 units in length and width

Step-by-step explanation:

We can factor 5 + 6 into the area equation L x W = A = 5 x 6 = 30

We have not considered other numbers because we can factor numbers such as 10 + 3 into the square area that Marcie calculated at 30 sq units, but they are less likely numbers given the description of mat.

It would be unlikely, that it was 10 length + 3width as the description would have been a narrow mat or runner.