Find the missing number:

20%

Step-by-step explanation:

If you see they say that the number decreased is 10% each and they say it two times. we could see that the missing number is as big as the length of two 10% together, so if you add them two you get 20%.

to find the perimeter of the rectangle this is the expression:

x-9+x-9+3x-4+3x-4=138

if we simplify it:

8x-26=138

remember, 138 is what it all adds up to

the length is 11.5cm

the width is 57.5cm

the area is 661.25cm^2

the answers might not be correct use at own risk