It will be 4f-30. Using substitution, you get (-8f-12) + (12f-18). Adding this together you get -8f-12+12f-18. Then you add -8f and 12f to get 4f, and add -12 and -18 to get -30.
The 9 is a coefficient because it is the first one before an 'algebraic number'. :)
Answer:
B) 15.7
Step-by-step explanation:
AB = 6
BC = 3
AC^2 = 6^2 + 3^2 = 36 + 9 = 45
AC = √45 = 6.7
Perimeter = AB + BC + AC
= 6 + 3 + 6.7
= 15.7
