a twaler caught 1/2 ton of fish monday and 1/2 ton of fish tuesday,but had to throw back 3/7 ton.how many tons of fish remained from the two days catch.

=1/2+1/2-3/7.

=1-3/7

=(7-3)/7.

=4/7 .

3/7 ton of fish remained with him after two days of catch.