1/15÷3.25+8/13×4/15+4/13÷3.75
=1/15÷(13/4)+8/13×4/15+4/13÷(15/4)
=1/15×(4/13)+8/13×4/15+4/13×(4/15)
=1/15×(1/13)×(1×4+8×4+4×4)
=1/15×(1/13)×4×(1+8+4)
=4/15