This is a cross-number puzzle. You need to place a digit (0-9) in each cell, so that the labelled numbers (read across & down like a crossword) satisfy the given equations. By convention, numbers never start with the digit '0'.
| X↓ | Y↓ | Z↓ | ||||||
| A → | X = 3J | |||||||
| B → | Y = 2K | |||||||
| C → | X + Y = Z | |||||||
| A + B = C | ||||||||
| J → | ||||||||
| K → | J + Z = C | |||||||