What is the solution of a system definded by y=-x+5 and 5x+2y=14?

Which value is not a solution of 8x^3 – 1 = 0

The angle of a triangle are given as 6x,(x-3), and (3x+7). find x then find the measures of the angles

Which of these equations, when solved, gives a different value of x than the other three? a9.1 = -0.2x + 10 b10 = 9.1 + 0.2x c10 – 0.2x = 9.1 d9.1 – 10 = 0.2x