A1=-15
a2=a1+d→-4=-15+d→d=11
The Pythagorean theorem is a^2 + b^2 = c^2. You use it when solving for the sides of a triangle.
The solution would be the coordinates of (3a,a).
A because x is the original price, so you multiply by the tax (9%) which would convert to 1.09 which you would multiply to the x
