:katie is 4 years younger than sylvia. let k represent katie’s age, and let s represent sylvia’s age. part a using the variables defined above, write an equation that shows the relationship between katie’s age and sylvia’s age. part b use the equation from part a to find how old sylvia is when katie is 13 years old. years old.

Part A:

Part B: 17 years old.

Step-by-step explanation:

Let be "k" Katie’s age, and "s" Sylvia’s age.

 Part A

According to the information given, Katie is 4 years younger than Sylvia. This meanas that we can find Katie's age subtracting 4 years from Sylvia's age.

Therefore, we can write the following equation that  shows the relationship between Katie’s age and Sylvia’s age:

Part B

In order to find Sylvia’s age when Katie is 13 years old, you must substitute into the equation and then solve for "s":

19

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