Simplify the expression. 

Write your answer in its simplest form and as an improper fraction.

$\frac{3a}{4}+\frac{a}{2}$

Simplify the expression. 

Write your answer in its simplest form and as an improper fraction.

$\frac{3b}{5}+\frac{7b}{15}$

Simplify the expression. 

Write your answer in its simplest form and as an improper fraction.

$2c+\frac{c}{3}$

Copy and complete the following:

$2\left(x+9\right)=2\times x+2\times 9$

$=2x+$_____

Copy and complete the following:

$3\left(y-1\right)=3\times y-3\times 1$

$=3y-$_____