A laptop was marked $300. I was able to buy it at a 20% discount and sold it at 15% profit.
How much did I sell it for?

$276

Step-by-step explanation:

300*0.2 = 60, 300-60=240, 240*1.15 = 276.

10.4 inches

step-by-step explanation:

2x2x2.6

let's call the solutions x₁ = (5 - 2√7)/3 and x₂ = (5 + 2√7)/3

then the equation is (x-x₁)(x-x₂) = 0

if you fill that in you get a lot of numbers which you can recognize as ax²+bx+c=0.

step-by-step explanation:

you can see that a=1 (there is just an x²)

b = (-5 -2√7 + 2√7 - 5)/3 = -10/3

c = -2√7)/3 ) * (-5+2√7)/3) = -1/3

so your answer is 3x^2 – 10x – 1 = 0