The cost of a barrel of oil has recently increased by 20% and is now selling for $72.00. how much was the barrel of oil before the increase?

Step-by-step explanation:

Let

x------> the cost of the barrel of oil before the increase

we know that

so

Solve for x

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

the correct answer would be:

220 centimeters

to get this you can use the pythagorean theorem

hope this

step-by-step explanation: