Subtract 9x^2+20x-50 from 13x^2-10x+12 someone please help

(13x^2 - 10x + 12) - (9x^2 + 20x - 50)

13x^2 - 10x + 12 - 9x^2 - 20x + 50

13x^2 - 9x^2 = 4x^2

- 10x - 20x = -30x

12 + 50 = 62

4x^2 - 30x + 62

2.2°  

step-by-step explanation:

let θ = the angle of elevation.

tanθ =77/2020

tanθ = 0.038 12

      θ = tan⁻¹0.038 12

      θ = 2.2°

we have three similar triangles, because each has a right angle and shares an angle.   let's write the angles in order: opposite to short leg, long leg, hypotenuse.

cab similar to bad similar to cbd

or as ratios,

ca: ab: cb = ba: ad: bd = cb: bd: cd

we also know

ac = ad + cd

(ad+cd): ab: cb = ba: ad: bd = cb: bd: cd

(ad+cd)/cb=cb/cd

we have cb=6, ad=5 and seek x=cd.

we reject the negative root and conclude x=4

answer: 4