qv and qp relationship
Let us assume that the initial and final temperatures in both the isobaric and isochoric processes are same. We will limit this discussion to ideal gases only. To calculate heat transfered we will use the expression $$q = nC\Delta T$$ Here C is molar heat capacity of the gas. For isobaric process, this will be $$q_p = nC_p\Delta T$$ For the isochoric process $$q_v=nC_v\Delta T$$
$\Delta T$ for both these processes same. Substracting these two equations we get $$q_p - q_v = n(C_p - C_v)\Delta T$$ The value of $C_p - C_v$ is $R$. Therefore $$q_p - q_v = nR\Delta T$$