Three Moles of an Ideal Gas with a Molar Heat

Three moles of an ideal gas with a molar heat capacity at constant volume of 4.9 cal/(mol∙K) and a molar heat capacity at constant pressure of 6.9 cal/(mol∙K) starts at 300 K and is heated at constant pressure to 320 K, then cooled at constant volume to its original temperature. How much heat flows into the gas during this two-step process?

A) 710 cal
B) -720 cal
C) 0 cal
D) 120 cal
E) -120 cal