how to show my daughter to do this and it needs to be changed to a mix number.

Solution 1 by separating parts
Rewriting our equation with parts separated
−5/6 −2−1/10
Solving the fraction parts
−5/6−1 1/0=?
Find the LCD of 5/6 and 1/10 and rewrite to solve with the equivalent fractions.
LCD = 30
−25/30−3/30= −28/30
Reducing the fraction part, 28/30,
−28/30= −14/15
Combining the whole and fraction parts
−2−14/15= −2 14/15
Solution by Formulas
converting mixed numbers to fractions, our initial equation becomes,
−5/6−21/10
Applying the fractions formula for subtraction,
=(−5×10)−(21×6)6×10
=(−50−126) / 60
= −176 / 60
Simplifying -176/60, the answer is
= −2 14/15
I hopes this helps!!! :)