How can I fix the vertical spacing between the numerator and the division symbol when entering fractions.
Eg. in the following code, the spacing between a and the division symbol is greater than one between b and the next (lower) division symbol.
\[ x = \dfrac{\dfrac{a}{b}}{c} \]


\mathstrutin the denominator of the inner fraction, so it will be raised a bit. – egreg Sep 16 '12 at 21:13ain the numerator is higher because you might have something like\[\frac{a}{2}\frac{f}{4}\]. – egreg Sep 16 '12 at 21:49\[ \phi = \frac{\dfrac{\text{fuel}}{\text{oxidizer}}} {\left(\dfrac{\text{fuel}}{\text{oxidizer}}\right)_{\text{st}}} \]. I could so something like\[ \phi = \frac{\text{fuel}/\text{oxidizer}} {(\text{fuel}/\text{oxidizer})_{\text{st}}} \]but found the former one easier to read. Later on I try to substitute in the numbers which are in the(a/b)/cform. Alsomathstrutworked\[ x = \dfrac{\dfrac{a}{\mathstrut{b}}}{c} \]. – mythealias Sep 16 '12 at 22:29\text{\raisebox{-.4ex}{fuel}}if you really like to reduce the vertical space. – egreg Sep 16 '12 at 22:47