(икс+3.29)умножить на 5 =42.35 3.7+8икс =20.5

8x=20.5-3.7

8x=16.8

x=16.8(делить)8

x=2.1

(х+3.29)*5 =42.35

5х+16.45=42.35

5х=42.35-16.45

5х=25.9

х=25.9:5

х=5.18

проверка (5.18+3.29)*5 =42.35

               (25.9+16.45)=42.35

2) 3.7+8х =20.5

    8х=20.5-3.7

    8х=16.8

    х=16.8:8

    х=2.1

проверка 3.7+8*2.1 =20.5

                3.7+16.8=20.5