1)
a/ (2/3-3/4):-5/12=(8/12-6/12) . -12/5=1/6 .-12/5=-2/5
b/ 5/7 .5/11 +5/7+2/11 -5/11.14/7
=5/7.(5/11+2/11)-5/11.14/7
=5/7.7/11-5/11.14/7
=5/11-5/11.14/7
=5/11.(1-14/7)
=5/11.(-1)
=-5/11
c/ 75% - ( 1,25 - 2/3/4) :3²/9
=3/4-(5/4-11/4): 9/9
=3/4+3/2
=3/4+6/4
=9/4
2)
a/ -3/5+x=1/3 b/ -8-x/15=-6/5 c/ l1/1/4-xl=0,2
x = 1/3+3/5 (-8-x).5=15.(-6) l 5/4-xl=0,2
x= 5/15+9/15 -40-5x =-90 ⇒5/4-x=0,2 hoặc 5/4-x=-0,2
x=14/15 5x = -40+90 ⇒1,25-x=0,2 hoặc 1,25-x=-0,2
vậy x=14/15 5x=50 ⇒x=1.25-0.2 hoặc x=1,25+0.2
x=10 ⇒x= 1,05 hoặc x=1,45
Vậy x=10
