Make a list of all invertible elements of z/20z along with their inverses (under the multiplication operation).

Step-by-step explanation:

We are given that

We have to find the invertible elements of along with their inverses under multiplication.

We know that

U(20)={1,3,7,9,11,13,17,19}

Operation used

Identity element=1

Inverse condition  :

Inverse of 1=1

Inverse of 3

()

Inverse of 3=7

Inverse of 7=3

Inverse of 9

Inverse of 9 is 9 .

Inverse of 11

11 is also self inverse element.

Where 1 is remainder

Hence inverse of 13 is 17 and inverse of 17 is 13.

19 is also self inverse element.

Therefore,

23

step-by-step explanation:

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