Which formula can be used to solve problems related to the first law of thermodynamics?

Q = ΔU + W

Q is the exchanged heat.

ΔU is the total change in the internal energy of a system.

W is the work done by or on the system.

The statement of the First Law is Thermodynamics is: "energy can be converted from one form to another with the interaction of heat, work and internal energy, but it cannot be created nor destroyed, under any circumstances".