Question

Two blocks, A and B, are placed on top of each other on a table. Block A's mass is 5 kg and block B's mass is 10 kg. Block A is placed on block B. What is the reaction the table gives onto the blocks?

Answer 1

Normal force in this case would be the force the table applies to the blocks, now A and B, in order to support them. You can read up more on it here and what causes it: https://energyeducation.ca/encyclopedia/Normal_force

The equation force given by N is: \[N = mg\]
Where normal force is gravity times mass.
Add the total mass 5+10 and multiply the sum by whatever number for gravity your teacher has you use (usually 9.8 but some do 10 or 9.81).