The air in an inflated balloon (defined as the system) is warmed over a toaster and absorbs 130 J of heat. As it expands, it does 78 kJ of work.
What is the change in internal energy for the system? Express your answer using two significant figures.
Delta E = kJ
I am just learning about heat and energy and i am a little confused about the signs (when a system is positive or negative/ when work is positive or negative). Also would i have to convert J to kJ first to use it in the equation :Delta E = q+w