Look at the graph thoroughly .
It passes through origin and given some points
(-1,1)
(1,-1)
(2,-2)
(-2,2)
We observe that

Hence whatever the function be the result will be -x
Option D is correct
Use photo math it’s on the App Store
You multiply 86 by 42.5 because each board is 42.5 and there are 86 boards.
The missing number is 15. .