The answer is C. Have a nice day.
Answer:
b = 12
Step-by-step explanation:
Complementary angles add to 90 degrees
a+b = 90
78+b = 90
Subtract 78 from each side
78-78+b = 90-78
b = 12
Answer:

Step-by-step explanation:

3x -4 (5 - x) = 7x -20
3x-20+4x=7x-20
7x-20=7x-20
Lets solve this step by step.
8 * 8 = 64
Lets suppose there are 8 aquariums and there are 8 fish in each. Therefore, there are 8 groups of 8 fish. Add and solve.
8+8+8+8+8+8+8+8 = 64