Answer: -43/60
To find this answer, you must first make the denominators of each fraction the same. To do so, multiply -5/12 by 5/5 to get -25/60 and multiply 3/10 by 6/6 to get 18/60. Finally, you subtract the fraction. Keep in mind, the denominators stay the same (60) while the numerators are subtracted. -25 - 18 is -43. Thus making the answer -43/60.
I hope this helps!