How to write the following expressions in expanded form for 4(x+y), 8(a+3b), 3(2x+11y), 9(7a+6b), c(3a+b), and y(2x+11z)

To write an expression in expanded form, simply times the number outside the bracket with the numbers/letters inside the bracket.

I'll show my working out.

4(X + Y)

times four by the letters inside the bracket.

(4 x X) + (4 x Y)

this leaves us with

4x + 4y

8(a + 3b)  --> (8 x a) + (8 x 3b) = 8a + 24b

3(2X + 11Y) --> (3 x 2X) + (3 x 11Y) = 6x + 33y

9(7a + 6b) --> (9 x 7a) + (9 x 6b) = 63a + 54b

c(3a + b) --> (c x 3a) + (c x b) = 3ac + bc

y(2x + 11z) --> (y x 2x) + (y x 11z) = 2xy + 11yz

remember when you times 'letters' (eg. x,y,z) together, you simply write them next to each other (eg. a x b=ab).