How will the area of the rectangle change if one side of it is doubled, and the other is 4 times?

Let a be the width of the original rectangle and b its length. Then the area of such a rectangle is calculated by the formula: S1 = ab.
Now we will increase the width of the rectangle by 2 times, we get 2a. We will increase its length 4 times, we get 4b. Thus, the area of the new rectangle will be: S2 = 2a * 4b = 8ab.
To find out how many times the area of the rectangle has increased after increasing its length and width, we divide the larger area into a smaller one:
S1 / S2 = 8ab / ab = 8.
Answer: the area of the rectangle has increased by 8 times.