A system absorbs 191 kj of heat and the surroundings do 120 kj of work on the system. what is the change in internal energy of the system?

The change in internal energy of the system is that there is an increase of 306kj in internal energy.

By using the first law and sign convention;

ΔE ₍int₎ = Q - W

But Q ₍int₎ greater than 0

W ₍int₎ less than 0

in convention

So,

ΔE ₍int₎ = Q - W

= 186 - (-120)

= 186 + 120

=306 kj