To divide rational numbers, we multiply the first number by the reciprocal of the second number.

So, 100/-245 ÷ -25/12 can be written as 100/-245 × 12/-25.

Multiplying the numerators and denominators, we get:

(100 × 12) / (-245 × -25)

= 1200 / 6125

= 48/245

Therefore, 100/-245 ÷ -25/12 is equal to 48/245.