A system of two blocks is shown in figure. Friction coefficient between 5 kg and 10 kg block is μ=0.6 and between 10 kg and ground is μ=0.4. What will be the maximum value of force F, which is applied at the lower block so that 5 kg block does not slip over 10 kg block? (g=10 m/s2) The force applied at the upper block is having fixed magnitude of 80 N (both forces start to act simultaneously).