Cubic and Quartic Functions Problems: Part 3

I am having trouble with a couple of questions in terms of the proccess of solving the questions:

**4 **A cuboid (recatangular prisim) has dimensions x metres, h metres and 4x metres. The cuboid is made of 640m of wire

**a** Find h in terms of x

**b** Find the volume, Vm^3 of the cuboid in terms of x

**c** Find V when x = 11

**d** Find the possible values of x for the cuboid to exist

**e** Find the possible values of x when V = 60,000 (give 2 decimal places**)**

**f** Find the max volume of the cuboid and the value of x for which it occurs

That is a long list of questions, and I will be greatly apprecieated if any of you would have the time to help and explain these questions for me.