Hi,

No one but mathematics textbook authors use such bizarre wordings. It always seems to me that the intent is to obfuscate the problem rather than illuminate it.

Suppose Justin caught $J$ fish and his father caught $F$ fish. "Three times the number of fish that Justin caught" is then $3 \times J.$ This number exceeds 12 and hence it is more than 12 and the amount by which it exceeds 12 is $3 \times J - 12.$

"5 times the number that his father caught" is $5 \times F$ and the amount that this exceeds 8 is $5 \times F - 8.$

These two quantities are equal and hence

\[3 \times J - 12 = 5 \times F - 8.\]

Together they caught 12 fish so that gives you a second equation

\[J + F = 12.\]

Solve these two equations for $J$ and $F.$

Write back if you need more assistance,
Harley