a, 21/25 . 11/9 . 5/7
= ( 21 . 11 . 5 ) / (25 . 9 . 7)
= ( 3 . 7 . 11 . 5 ) / ( 5 . 5 . 3 . 3 . 7 )
= 11 / ( 5 . 3 )
= 11/15
b, 5/23 . 17/26 + 5/23 . 9/26
= 5/23 . ( 17/26 + 9/26 )
= 5/23 . 26/26
= 5/23
c, ( 3/29 - 1/5 ) . 29/3
= 3/29 . 29/3 - 1/5 .29/3
= 1 - 29/15
= -14/15
d,5.7/5
= 35/5
=7
e,3/4.7/9+1/4.7/9
= (3/4+1/4) .7/9
=1.7/9
=7/9
g,1/7.5/9+5/9.1/7+5/9.3/7
= 5/9.(1/7+1/7+3/7)
=5/9.5/7
=25/63
h,4.11.3/4.9/121
=4.11.3-4.3.3/11.11
=4/4.11/11.3/3.1/11
=1.1.1.1/11
=1/11