Joni usually buys 20 pounds of dog food at the pet store for $19.95. she gets a coupon in the mail for 15% off a 10 pound bag, normally priced at $12.95. which is cheaper per pound?

19.95

Step-by-step explanation:

This is one of those questions that are a must do. The process is called estimation and if you follow it carefully, you learn a lot.

Round 19.95 to 20

Round 12.95 to 13 dollars. You get 15% off. which is about (1.50 + 0.75 = 2.25)

This the 10 pound bag down to 13 - 2.25 = 10.75. This is higher than 1 dollar per pound.

20 pounds for 20 dollars = 1 dollar per pound.

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