В) 7/8+5/8*1/3+2/3 г) (1/6+3/14):(5/21-1/14)

Приведем дроби к общему знаменателю.

в) 7/8 + 5/8 * 1/3 + 2/3 = 7/8 + 5 * 1 / 8 * 3 + 2/3 = 7/8 + 5/24 + 2/3 = 21/24 + 5/24 + 16/24 =

= 42/24 = 2;

г) (1/6 + 3/14) : (5/21 - 1/14) = (7/42 + 9/42) : (10/42 - 3/42) = 16/42 : 7/42 = 16/42 * 42/7 =

= 16/7 = 2 2/7.