Since there's no GCF here, you multiply the first and third terms, giving you -240. Your next step is to find two numbers that have a sum of 8 and a product of -240. These numbers are 20 and -12. Plug those in and you've got:
16x^2 + 20x - 12x - 15
From here you divide it into two binomials. These are (16x^2 + 20x) and (-12x - 15). When you take out the greatest common factors (4x and -3), they become:
4x(4x + 5) - 3(4x + 5)
Then you group what's outside of the parentheses together (4x - 3) And bring what's inside of the parentheses down (4x + 5). This brings your answer to
The first step to dividing fractions is to find the reciprocal (reverse the numerator and denominator) of the second fraction. Next, multiply the two numerators. Then, multiply the two denominators. Finally, simplify the fractions if needed.