A since it’s being change along the x-axis
Area of a triangle is equal to 1/2 b(h) so since you already have the height and base, all you need to do is input it back into the equation:

(10)(13)
Multiply 10 & 13 to equal

(130)
Then take half of 130 to get
A = 65
It will take 72 hours to make 63 carvings
The correct answer will be -4x - 10 which is A. X subtracts to the other side and makes it -4x, then 6 +-4 = -10
Your answer should be 76/45