To simplify this:

You can factor the denominator and then cancel out some terms. But, this is not factorable. So, I think you are missing a term or you wrote this wrong.
3/4 x 1 = 3/4 x / = 21/28
?/? = 7/7
let's keep in mind that, in the II Quadrant, cosine is negative and sine, is positive.
cosine is adjacent/hypotenuse, however the hypotenuse is simply a radius unit, and thus is never negative, so in the -(2/3) the negative must be the numerator, -2.

Decimal: 5.0
Fraction: 5/1
1/9
2/1
i am working on the last one but i hope i helped