Tasha's mistake is in Step 4
she has a negative sign in front of the fraction and she has a negative exponent on the 4 in the denominator
Answer:
An equivalent fraction is 12/21
Distribute the

And combine the s terms and you should be able to solve it
Answer is - 10
Step-by-step explanation:
Let the missing number be ‘x’
-8-x = 2
-x = 2 + 8
-x =10
x = -10