Answer: 3 days
Step-by-step explanation: It would take 3 days for seven hens to 7 lay eggs because each hen lays an egg each day.
1 hen/1 egg = 3 days
7 hens/7 days = 14 eggs
7 hens/3 days = 7 eggs
Answer: b=-12
Step-by-step explanation:
120/-10 = -12
-10b/-10 = b
b=-12
Check the picture below.
thus is at 0 = -16t² + 96t +640,

well, clearly it can't be a negative value for the elapsed seconds, so it can't be -4.
Answer:

Step-by-step explanation:
{x -4y = −21
{8y - x = 45
_________

[Plug this back into both equations above to get the x-coordinate of 3]; 
I am joyous to assist you anytime.