I believe the answer would be a!
Answer:

Step-by-step explanation:
Let x represents the number of nights Jack worked and y represents the number of nights Diane worked.
1. The number of nights Diane is scheduled to work is no more than four times the number of nights Jack is scheduled to play. Then

2. Diane will work at least 10 times before the concert. Then

3. Jack earns $50 per night that he plays, then he earned $50x in x nights. Diane earns $25 each night she works, then she earns $25y in y nigths. They need at least $750, so

4. We get the following set of constraints to model the problem:

Answer: The mass of the object is 10 kg
Step-by-step explanation:
According to Newton's second law of motion, the force
applied to an object with mass
is directly proportional to its acceleration
:
(1)
If we isolate
:
(2) This means the acceleration of the object varies inversely with its mass
Now, we are given the following data to calculate a constant force using (1):

(3)
(4)
(5)
If we apply this same force calulated in (4) in another object with an acceleration of
, its mass
will be:
(6)
(7)
Finding
:
This is the mass of the object