Answer:
You're correct, the answer is 12.
A. definition of right angle
B. substitution property
C. definition of congruent angles
Multiplying fractions: multiply numerators and multiply denominators
1. 3/4 X -6/7 = -18/28 = -9/14
2. -2/7 X -3/7 = 6/49
3. 4 because 72/9 is 8. -72/-9 is 8. Two negatives makes a positive when multiplying and dividing.