[求助]prep的一道题

老外的解释：

The description of how cost is proportionate to length and thickness can be converted to an equation as follows:

Cost = k x Square(Length) x Thickness, where k is a constant.

We are now asked to find the cost, for a slab of given length and thickness. In order to find the cost, we need to determine the constant "k".

Statement (1): The cost of a square slab that is 2 meters long and 0.2 meters thick is $160 more than the cost of a square slab that is 2 meters long and 0.1 meter thick

So that means k x Square(2) x 0.2 = k x Square(2) x 0.2 + $160
From the above equation you can determine "k". So we can plug this in the equation to find the cost of the 3 meter long slab. HENCE SUFFICIENT.

Statement (2): The cost of a square slab that is 3 meters long and 0.1 meters thick is 300 more than the cost of a square slab that is 3 meters long and 0.1 meter thick. The above statement is very similar to Statement (1), except for the difference in dimensions and costs. So this statement is also SUFFICIENT to determine the cost.

Hence answer is (D).