What are a platform’s two major components?

Operating System and the CPU.

Explanation:

Any program is made to run on a particular platform. And a platform comprises of the operating system and the CPU. And by CPU we mean the processor type. Like its 64 bit or 32 bit, and also how many cores they are. Like a Quad-core processor allows the parallel running or 4 tasks, or 4 tasks at one time. The GPU feature defines the graphics, and what graphics are allowed for programming. Also, features like Emulator requires special features in the microprocessor.

3/4 times 18= 13.5
31.5-13.5=18 
It cost 18 dollars for the skirt with a discount.
It cost 13.5 for the blouse as opposed to the original price of 18 dollars.
18(skirt)+13.5(blouse)=31.5
If you set up a proportion to find the original price of the skirt you will get the answer. 
18/x=75/100
75x=18 times 100
75x=1800
75x/75=1800/75
x=24 
The original price of the skirt is 24 dollars.