Answer: -3/4
Step-by-step explanation: Remember that dividing by a fraction is the same thing as multiplying by the reciprocal of that fraction or that fraction flipped.
In other words we can rewrite 9/10 ÷ -6/5 as 9/10 · -5/6.
Before multiplying however, notice that we can cross-cancel
the 9 and 6 to 3 and 2 and the 5 and 10 to 1 and 2.
So we now have 3/2 · -1/2.
Now multiplying across the numerators
and denominators we get -3/4.