Hi there!
Recall the equation for electric potential of a point charge:

V = Electric potential (V)
k = Coulomb's Constant(Nm²/C²)
Q = Charge (C)
r = distance (m)
We can begin by solving for the given electric potentials. Remember, charge must be accounted for. Electric potential is also a SCALAR quantity.
Upper right charge's potential:

Lower left charge's potential:

Add the two, and subtract from the total EP at the point:

The remaining charge must have a potential of 2036.25 V, so:

Explanation:
Transparent objects do not form shadows. The light passes completely from the transparent objects thus these objects will not form shadow. ... In such objects, the light gets refracted thus, such objects forms shadow. The refraction is also the reason why we can see such objects.
Answer:
Heat energy required (Q) = 3,000 J
Explanation:
Find:
Mass of water (M) = 200 g
Change in temperature (ΔT) = 15°C
Specific heat of water (C) = 1 cal/g°C
Find:
Heat energy required (Q) = ?
Computation:
Q = M × ΔT × C
Heat energy required (Q) = Mass of water (M) × Change in temperature (ΔT) × Specific heat of water (C)
Heat energy required (Q) = 200 g × 15°C × 1 cal/g°C
Heat energy required (Q) = 3,000 J
I believe your answer is correct, because 8.7*10^-7 is equal to 0.00000085347.
Hope you do well!