Divide the sum of -13/5 and 12/7 by the product of -31/7 and -1/2

Let's compute the two factors separately: as for "the sum of -13/5 and 12/7", we have to rewrite the two fractions so that they have the same denominator. Since the least common multiple of 5 and 7 is 35, we will change both fractions so that they have denominator 35:

So now we can sum them:

Multiplication is easier, since you just have to multiply numerators and denominators with each others:

Finally, we must divide the two fractions. Dividing by a fraction is the same this as multiplying by the inverse of that fraction, i.e. we have to switch numerator and denominator: