A perimeter increased by four is twenty eight.
(As an equation)

P+4=28, meaning that the original perimeter was 24

Step-by-step explanation:

Let's call the perimeter P.

Converting the words into an equation, you get:

P+4=28

Now, you can subtract 4 from both sides:

P+4-4=28-4

P=24

Hope this helps!

20

step-by-step explanation:

by definition, an arc subtended by a central angle of some given measure has the same measure. so .