What is the answer to 5 kg minus 730 g?

If y varies directly as x2 and y=6 when x=6, find the constant of variation.

Ellie spent $88.79 at the computer stote. she had $44.50 left to buy a cool hat. how much money did she originally have? write and solve an equation to answer the question.

Ineed to know how to write question one in mathematical terms