[Math]

someone help please!!

can you show me how to do these problems:

f(x)= square root of x

g(x)= 1-2x

1) (fog)(x)

2) (gof)(x)

3) (fog)(-4)

4) (gof)(-4)

5) 2g(-1) - 3g(-1)

6) 2f(-9)

the answers are as follows:

1. square root of (1-2x)

2. 1 - (2 sqrt of x)

3. 3

4. 1-4i

5. -3

6. 6i

i just need to know HOW to get the answers!!

please and thank you