Answer
$\frac{12}{7}$ hours
Work Step by Step
Let $x$ be the hours to weed the garden together. Then
$$
\frac{1}{3}+\frac{1}{4}=\frac{1}{x}
.$$
Solving for $x$ results in
$$\begin{aligned}
12x\left(\frac{1}{3}+\frac{1}{4}\right)&=12x\left(\frac{1}{x}\right)
\\
4x+3x&=12
\\
7x&=12
\\
x&=\frac{12}{7}
.\end{aligned}$$
Hence, weeding the garden together will take $\frac{12}{7}$ hours.
