A. define the variables : a = abby's miles, j = james' miles
b. a = j + 4......j = a - 4
c. a + j = 28
a = j + 4
d. (j + 4) + j = 28
2j + 4 = 28
2j = 28 - 4
2j = 24
j = 24/2
j = 12
a = j + 4
a = 12 + 4
a = 16
e. check..
a + j = 28
16 + 12 = 28
28 = 28 (correct)
solution is : abby's miles (a) = 16
james' miles (j) = 12
My guys is is not just (5, -10)?
If one game needs two* players, and there are 5 games,
you multiply two by five to get ten players total.
The unit circle is a circle with radius

, so you have

where

is measured in radians, so

.