Which is most likely the first step in solving a system of nonlinear equations by substitution?
a. substituting a number for one of the variables
b. substituting one equation into the other equation
c. isolating a variable in one of the equations
d. taking the square root of both sides of one of the equations

C.Isolating a variable in one of the equations

Step-by-step explanation:

answer: 204

step-by-step explanation:

we are told that the revenue is

x⋅(4080−10x)=−10x^2+4080x

this is a quadratic function, so to maximize it we should find the x-value of its vertex. recall that the x-value of the vertex of the parabola ax^2+bx+c is given by the formula −b/2a.

so in this case, we have a=−10 and b=4080, so the x-value of the vertex is

−b/2a= −(4080)/2(−10)=204

6e14 is the answer.