a) 5y+(8y+9)=100 б) x-(50-x)=12 в) 30-x=3(20-x)

a) 5y+(8y+9)=100
б) x-(50-x)=12
в) 30-x=3(20-x)

  • 5y+(8y+9)=100

    5y+8y+9=100

    13y+9=100

    13y=100-9

    13y=91

    y=91/13

    y=7

    x-(50-x)=12

    x-50+x=12

    2x-50=12

    2x=50+12

    2x=62

    x=62/2

    x=31

    30-x=3(20-x)

    30-x=60-3x

    2x-30=0

    2x=30

    x=30/2

    x=15

  • а) 13 y+9 = 100

    13 y-91 = 0

    y = 7

    б) 2 x-50 = 12

    2 x-62 = 0

    x = 31

    в)

    30-x = 60-3 x

    2 x-30 = 0

    x = 15