Round 53642 to its tens place​

Atriangular bandana has an area of 46 square inches. the height of the triangle is 5 3 4 inches. enter and solve an equation to find the length of the base of the triangle. use b to represent the length of the base.

Simplify. −4x^2 (5x^4−3x^2+x−2) −20x^6−12x^4+8x^3−8x^2 −20x^6+12x^4−4x^3+8x^2 −20x^8+12x^4−4x^2+8x −20x^6+12x^4+4x^3−8x^2

Having a hard time understanding this question (see attachment).