Question

    tìm x
a) X x 3/4 = 1/5      b) 3/7 x X = 2/5      c) 1/3 + 2/9 = 2/12 x X     
d) 4/15 x X - 2/3 = 1/5     e) x : 1/7 = 2/3         f) 1/9 : x = 7/3      j) 1/4 + 5/12 = 8/3 : x
 h) 7/4 : X - 1/2 = 1/5

Answer 1

a: x*3/4=1/5

=>x=1/5:3/4=1/5*4/3=4/15

b: x*3/7=2/5

=>x=2/5:3/7=2/5*7/3=14/15

c: 1/3+2/9=2/12x

=>1/6x=3/9+2/9=5/9

=>x=5/9*6=30/9=10/3

d: 4/15*x-2/3=1/5

=>4/15*x=2/3+1/5=10/15+3/15=13/15

=>4x=13

=>x=13/4

e: x:1/7=2/3

=>x=2/3*1/7=2/21

f: 1/9:x=7/3

=>x=1/9:7/3=1/9*3/7=3/63=1/21

j: 1/4+5/12=8/3:x

=>8/3:x=3/12+5/12=8/12=2/3

=>x=4

h: =>7/4:x=1/5+1/2=7/10

=>x=7/4:7/10=10/4=5/2