20*(3+2)= 100.

A Washing dishes 9-3 is more than washing dishes = 6.

B Washing dishes is 7-2 more than washing dishes = 5.

Actually, two people washed too much 134- 100=34.

34 is divided into integers 6 and 5.

34=6*4+5*2 (nothing else)

To explain, A washed dishes for 4 minutes, and washed 9*4=36.

B washed the dishes for 2 minutes, and washed 7*2= 14.

That is, there are 36+ 14=50 bowls.

License plate 134-50=84