Karina is making costumes for her dance team and she buys 3 1/2 metres of black material, 6 1/4 metres of red material, and 4 1/3 metres of yellow material. How much red material did she have

Karina is making costumes for her dance team and she buys  3 1/2 metres of black material, 6 1/4 metres of red material, and        4 1/3 metres of yellow material. How much red material did she have left? [HINT: multiply]

So basically I have to find the length that's left of the red material