Part 2 needed!

An ideal gas at temperature T₀ is slowly compressed at a constant pressure of 2 atm from a volume of 10 liters to a volume of 2 liters.

Then the volume of the gas is held constant

while heat is added, raising the gas temperature back to T₀

1 atm = 1.0×10⁵ Pascals and 1 liter = 0.001 m³

Part 1:

Calculate the work done ON the gas.

The answer to the first part is

1. −800 J

2. −400 J

3. +400 J

4. +1600 J

5. −1600 J

6. +800 J

+1600 J (I have this part already)

I converted the liters to .010 m³(V₀) and .002 m³(Vₓ) (final)

and 2 atm to 2.0 * 10⁵ Pa (pressure)

W=-p(Δv)

Work= negative pressure (final-initial Volume)

-2.0*10⁵(2-10)= +1600 J

**Part 2: Is the one I need

Calculate the heat flow INTO the gas

1. +800 J

2. −1600 J

3. −400 J

4. +1600 J

5. +400 J

6. −800 J

I don't understand the formula of the Universal Ideal Gas Law

ΔU= Q+W and how to apply it to this question, Help!**
Work is W and Q is the heat I believe and applied, all I know is it has to become
Q=-W