Answer:
By 19 percent
Explanation:
Lets take a square that has the side length 10. The area of this square is obviously 100. Now let's decrease the side length by 1% making the new side length 9. the area of this new square is 9x9 = 81. Now let's find the percentage:
(81/100) × 100% = 81%. this is the percent of area the new square is of the old one
100-81 = 19