Answer
The tension in the leftmost rope is 10 N. The tension in the middle rope is 20 N.
Work Step by Step
We see that 30 N pulls three equal-mass blocks. To pull the two blocks on the left then requires 20 N. This is the tension in the middle rope.
The tension in the leftmost rope that pulls only one block is 10 N.
Incidentally, the net force on the rightmost block is 30 N – 20 N = 10 N, as expected. The net force on the second block is also 10 N.
