You're correct, the answer is C.
Given any function of the form

, then the derivative of y with respect to x (

) is written as:

In which

is any constant, this is called the power rule for differentiation.
For this example we have

, first lets get rid of the quotient and write the expression in the form

:

Now we can directly apply the rule stated at the beginning (in which

):

Note that whenever we differentiate a function, we simply "ignore" the constants (we take them out of the derivative).
So u need to calculate 738 as a lines
Answer: Okay so do 3x7.5 then 3x11.5 then 7.5x11.5 then add it up and you should get 143.25
Answer:
73
Step-by-step explanation:
Original number: XY
x = 3y - 2
10y + x = (10x + y) / 2 + 1/2
substitution: 10y + 3y - 2 = 13y - 2 = (10 * (3y - 2) + y) / 2 + 1/2
* 2 both sides and simplify: 26y - 4 = 31y - 19
31y - 26y = -4 + 19
5y = 15
y = 3
x = 7
Original number: 73