4. Найди неизвестный член пропорции: а) 4.8:5.1 = y:3.4; b) z:5 = 7:11; c) 8:2 = 2:х.

a) 4.8/5.1 = y/3.4 => y = (4.8*3.4)/5.1 = 3.2. b) z/5 = 7/11 => z = (7*5)/11 = 35/11. c) 8/2 = 2/x => x = (2*2)/8 = 0.5.