A rectangle on a coordinate plane has a length of 5 units and a width of 3 units. If the rectangle is dilated by a scale factor of 5, what is its new area?
The answer is 375 square units.
The original area of the rectangle is 5 units * 3 units = <<5*3=15>>15 square units.
When the rectangle is dilated by a scale factor of 5, its new length becomes 5 units * 5 = <<5*5=25>>25 units.
Its new width becomes 3 units * 5 = <<3*5=15>>15 units.
Therefore, the new area of the rectangle is 25 units * 15 units = <<25*15=375>>375 square units. Answer: \boxed{375}.