Judging by the question you have provided I came to the conclusion that you have already solved your own problem!
If the goal is to find X when X=-15 then your answer for X should be -15!
If this is not the entire equation please post the entire one!
Hope this helped!
-Blake
The difference of the given fraction is expressed as 
Given the expression:
Take the LCM of the fraction to have:

Hence the difference of the given fraction is expressed as 
Learn more on fractions here; brainly.com/question/78672
The prime factorisation of 81 is 3^4(because 3*3*3*3 four times =81)
do not change the rest 3^4 m^2 x^3
Answer:
Length = 15
Width = 6
Area = 90
Step-by-step explanation:
Area of the rectangle = 
Lets factorise the polynomial


We know that Area = Length × Width
Let the length be (x + 3) & width be (x - 6)
Its given in the question that x = 12. So putting the value of x gives ,
Length = 
Width = 
Area = Length × Width = 15 × 6 = 90