The perimeter of the rectangle is 20 cm. One side is 6 cm long. What is the length of the missing side

it is 4cm long

Step-by-step explanation:

You multiply 6 by 2 to get 12, then subtract 12 from 20 and get 8. Then you divide 8 by 2 to get 4. If you want to check it, you can add 6+6+4+4 to get 20

4

Step-by-step explanation: the definition of a rectangle states that opposite sides of the rectangle are congruent. this means that there is 2 sides that measure 6cm. These two sides added together give us 12cm. By working backwards, we can subtract 12cm from the perimeter (20cm), this gives us 8cm. by diving that by 2 we can find the lenght of the missing sides, 4cm each.