Question

bai 1 , tim so tu nhien x , biet 

a, 5x+10=2x+70

b, 7x-2x-31=69

Answer 1

a, \(5x-2x=70-10\Leftrightarrow3x=60\Leftrightarrow x=20\)

b, \(5x=69+31=100\Leftrightarrow x=20\)

Answer 2

a: =>3x=60

=>x=20

b: =>5x=100

=>x=20

Answer 3

a, 5x+10=2x+70

    5x - 2x = -10 + 70

    x.(5 - 2 ) = 60

    x.3 = 60

    x    = 60 : 3

    x    = 20

b, 7x - 2x - 31 = 69

    x . ( 7 - 2 ) = 69 + 31

    x . 5 = 100

    x      = 100 : 5

    x      = 20

Answer 4

a, 

b,