20 / (Х + 30) + Х/15 =5
20 *15 + Х(Х + 30) = 5*15(Х+30)
300 +X^2 + 30X = 75X + 2250
X^2 + 30X -75X +300 - 2250 = 0
X^2 - 45X - 1950 = 0
D = 2025 -4*-1950 = 2025 + 7800 =Y9825
D = ~99,12
X1 = (45 + 99,12) /2 =144,12/2 = 72,06
X2 = (45 - 99,12) / 2 = - 54,12/2 = -27,06
X1 = 72,06
X2 = - 27,06