Simplify the following expressions :
`1/2 (a - 3b) - 2/3 (1/4 a - 4/3b)`

Simplify the following expressions : 2/3 (3a+ 6b ) - 5a - 2/5 b

Simplify the following expressions : 2/3 (2a-b) +1/2 (a-2b+c) - 1/3 c

Simplify the following : 1""2/3+2""1/2+3/4

Simplify the following : (1/4" of "2""2/7) div 3/5

Factorize each of the following expressions : 4a^2-9b^2-2a-3b

Add the following algebraic expressions : 2a - 3b + 4c , -3a + 2b - 5c , 7a - c and 3b + 6c

Simplify the following : (1""1/4+2""3/4) div (2""2/3+3""1/3)

Simplify : 2/3 (2a-3b) -3/4 (2a +5/3 b)

Factorize each of the following expressions: 36 l^2-(m+n)^2 (2) 25 x^4y^4-1 (3) a^4-1/(b^4) (4) x^3-144 x

Simplify and find the value of the following expression when a=3 and b=1: 4(a^2+b^2+2a b)-[4(a^2+b^2-2a b)-{-b^3+4(a-3)}]