Algebra ! Question 1F , question 3, question 4, question 6

1f:

\frac{c^2d^4}{c^4d^2}\frac{c^6d}{(cd)^2}=\frac{c^8d^5}{c^6d^4}=c^{8-6}d^{5-4}=c^2d

6a:

z=\frac{3-xy}{2} $$Multiply both sides by 2$$ 2z=3-xy $$Add xy to both sides$$ xy+2z=3 $$Subtract 2z from both sides$$ xy=3-2z $$Divide both sides by y$$ x=\frac{3-2z}{y}$$

Now let's see your attempt at some of them.