How to you solve %x 17=78

In a school 2/3 of the students study a language of those who study a language 2/5 study french

Solve 2x+y=3 x+y=5 in substitution method

The dolphins at the webster are fed 1/2 of a bucket of fish each day the sea otters are fed 1/2 as much fish as the dolphins how many buckets of fish are the sea fed each day? simplify you answer and write it as a proper fraction or as a whole or mixed number