The electric flux for Gaussian surface A that enclose the charged particles in free space is (given q1=−14nC, q2=78.85nC, q3=−56nC)

Flux is due to charges enclosed per ε0∴ Total flux =(−14+78.85−56)nC/ε0=8.85×10−9C×4π4πε0=8.85×10−9×9×109×4π=1000.4Nm2/C i.e. 1000 Nm2C−1