#### Answer

$\frac{3}{8}$

#### Work Step by Step

You are given the following:
$a=\frac{1}{2}$
$b=\frac{3}{4}$
You are solving for $ab$ or $a\times b$, and since you have the values for both $a$ and $b$, you can plug them in:
$\frac{1}{2}\times \frac{3}{4}$
To multiply fractions, you first multiply the numerators--the "numbers on top". The result will be the numerator of your answer.
$1\times3=3$
Then you multiply the denominators--the "numbers on bottom." The result will be the denominator of your answer.
$2\times4 =8$
Therefore, the final answer will be $\frac{3}{8}$.