To subtract two fraction we have to make common denominator. We can do this by multiplying or dividing numerator and denominator by the same number in one fraction.
Lets do this.
[tex] \frac{5}{12}- \frac{3}{8} = \frac{5*2}{12*2}- \frac{3*3}{8*3}= \frac{10}{24}- \frac{9}{24} = \frac{1}{24} [/tex] - its the result