6) 2,5 x : 7 = 1/28 :30
2.5 x / 7 = 1 / (28*30)
2.5 x * 28*30 = 7*1 2.5x = 7/ (28*30) 2.5x = 7/840 x = (7/840) :2.5
x = (1 / 120) * (1/2.5) x = 1 / 300
7) 2/5 = 8 / (x+2) 2*(x+2) = 5*8 x+2 = 40/2 x+2 = 20 x=20+2 x=18
8) 2/(x-0.5) = 1/0.3 2*0.3 = 1*(x-0.5) x-0.5 = 0.6 x = 0.6+0.5 x = 1.1