x = -21
explanation: a trick i used was just do -3 times 7 and get my answer -21. if you are unsure if the answer is right just check your work with a calculator. -21 divided by 7 is -3 so -21 is the value of x. please mark brainliest !!
Add numbers with the same amount of variables
-x^2 + (-7x^2) = -8x^2
– 28x (+ 14x )= -14x
7 (+ 8) = 15
-18x² - 14x + 15 is your answer
hope this helps
Answer:

Step-by-step explanation:
There was no figure but the question is clear
Volume of a cylinder is given by the formula
where r is radius of base of cylinder, h is the height
Volume of a cone is given by 
where r is the radius of base of cone, h is the height
The radius of the cylinder =
(diameter) =
(12) = 6cm
Height of cylinder = 15cm
Volume of cylinder 
Radius of cone =
(radius of cylinder) =
(6) = 3 cm
Height of cone same as height of cylinder = 15cm
Volume of cone, 
Difference is the volume of the remaining solid
