`#Kenshiro`
`a ) ( 1/3 + 2/5 ) xx 3/4`
Cách 1 :
`( 1/3 + 2/5 ) xx 3/4 = 5/15 + 6/15 xx 3/4 = 11/15 xx 3/4 = 33/60 = 11/20`
Cách 2 :
`(1/3 + 2/5) xx 3/4 = 1/3 xx 3/4 + 2/5 xx 3/4 = 3/12 + 6/20 = 60/240 + 72/240 = 132/240 = 11/20`
`b ) ( 7/9 + 2/3 ) : 5/6`
Cách 1 :
`( 7/9 + 2/3 ) : 5/6 = 13/9 : 5/6 = 13/9 xx 6/5 = 78/45 = 26/15`
Cách 2 :
`( 7/9 + 2/3 ) : 5/6 = ( 7/9 : 5/6 ) + ( 2/3 : 5/6 ) = ( 7/9 xx 6/5 ) + ( 2/3 xx 6/5 ) = 42/45 + 12/15 = 14/15 + 4/5 = 26/15`