Answer:
585/16
Explanation:
Assuming these are 3 separate fractions 15/4 and 13/4 and 12/4,
multiply all the numerators 15 x 13 x 12 = 2340
multiply all the denominators 4 x 4 x 4 = 64
This is your fraction answer
2340/64
You can reduce it by dividing numerator and denominator by 4
585/16