№ 114.
( 2/7 + 5/21 ) : 1 4/7= ( 6/21+5/21 ) : 11/7 =
= 11/21 * 7/11 = 1/3
(8/11 +3/22) : 5/11 = ( 16/22+3/22) : 5/11=
= 19/22 * 11/5 = 19/10= 1 9/10
№ 113.
3 1/5 : 2 2/5 = 16/5 * 5/ 12= 4/3 = 1 1/3
1 7/8 : 4 1/6 = 15/8 * 6/25 = (3*3) / (4*5) = 9/20
№115.
2/9 х = 5/12
х= 5/12 : 2/9 = 5/12 * 9/2 = (5*3)/(4*2)
х=15/8 = 1 7/8
Проверим:
2/9 * 15/8 = 5/12
(1*5) / ( 3*4) = 5/12
5/12=5/12