Im having some trouble with algebra, i cant find a good teacher and books just aren't explaining things properly for me, im new to algebra and really need some help with some problems! please help!!

My worksheet doesn't really explain things. how am i supposed to work out whats supposed to go in the .... area????
Here is how its displayed on my sheet. (i've put * for numbers that are squared)

1. Complete the following.
a) 4a + 20b = 4(...+...)
b) -a(t-1/2t*) = -at...
c) p*q+pq* = ...(p+q)
d) 11x - (5x + 8y) = 2........

What is a single fraction???? how do i convert these sums into single fractions with no common factors?

4. Write as a single fraction with no common factors.
a) 2a* - 4a
---------
2a

how do i do this??? i need an explanation that i can understand to be able to work out other problems in the future please help asap! thankyou!!!