Respuesta :

0.925x^2 - 4x + 20 = -1.125x^2 + 6x + 40 (at break even point)

2.05x^2 - 10x - 20 = 0

x =  [ - (-10) +/- sqrt(100 - 4*2.05*-20) / (2*2.05) 

x =  6.40, -1.52   Ignore the negative 

Answer is  6.40