Arectangle with sides 3 cm and 5 cm was enlarged in the ratio 1: 3

how did the area of the rectangle change?

The area was originally 3*5, or 15 cm^2.

When the sides were enlarged, they were all multiplied by 3. The new sides are 3*3, or 9, and 5*3, or 15.

The new area is 9*15, or 135 cm^2.

If you divide 135, the new area, by 15, the original area, you get 9. So, the area increased by a factor of 9.

.

step-by-step explanation:

b

step-by-step explanation:

a difference is the result of subtraction. while each of these expressions has subtraction in it, a difference will be the result when subtraction is the last operation applied in the order of operations for the expression. this means subtraction must be outside of the parenthesis. only b has this.