Incomplete question as the unit of volume is not written correctly.So the complete question is here:
A straightforward method of finding the density of an object is to measure its mass and then measure its volume by submerging it in a graduated cylinder. What is the density of a 240-g rock that displaces 89.0 cm³?
Answer:

Explanation:
Given data
Mass m=240g
Volume V=89.0 cm³
To find
Density d
Solution
If rock displaces 89.0 cm³ of water means volume of rock is also 89cm³
So

Answer:
A. 12,240.
Explanation:
1,530 times 8.0 = 12,240.
hope this helped :)
Answer: 6000N/m^2
Explanation:
Weight =1500N
Area =0.5m^2
Pressure =1500/(0.5^2)
=6000N/m^2
Note: Newton is denoted by 'N' (Capital) and use '^' for powers.
If the two waves have the SAME FREQUENCY and are exactly
out of phase (180° apart), then the resultant wave will have the
same frequency and an amplitude of 1 unit.
If the two waves do not have the SAME FREQUENCY, then their
relative phase is meaningless.
The way their suppose to do it