г)(2/3*4/5)*(3/4*5/6)*(6/7*8/9)*(7/8*9/10) "/"-дробная черта

(2/3*4/5)*(3/4*5/6)*(6/7*8/9)*(7/8*9/10) = 8/15*15/24*48/63*63/80 = 8/24*48/80 = 1/3 * 3/5 = 1/5 = 0,2