The answer is -75.
1. Convert the mixed fraction into an improper fraction. 6 x 4 is 24+1=25 and you keep the denominator. Thus it would be -12 x 25/4.
2. Cancel out the common factor. 12 and 4 are both divisible by 4. -12 divided by 4 is -3, and the four would cancel out.
3. We are left with -3 x 25 which would be -75, because a negative integer multiplied by a positive integer is negative.
Hope that helps. :)