For (a) and (b) did I do them right? thanks a lot

a is write, b is wrong

Step-by-step explanation:

b) difference is subtraction!

The question asks "the sine of a difference of two real numbers is not necessarily equal to the difference of the sines

So the first part is "the sine of a difference of two real numbers" would be writtten as : sin (x-y)

The second part, the difference of the sines,  would be: sinx - siny