Answer
23:42
Work Step by Step
You are asked for width to length, so it is important to put the width on top and the length on the bottom.
$\frac{46mm}{84mm}$
Reduce the fraction to its lowest form by dividing the top and bottom by two.
$\frac{23}{42}$
The ratio can be written as $\frac{23}{42}$ or 23:42