задача 1

(угол) ABC=72 (градусов)

DBC - ABD=26

DBC = ?

ABD = ?

задача 2

MNP=140

MNK : KNP = 2:5

MNK = ?

KNP = ?

1) ∠DBC+∠ABD=72°

∠DBC-∠ABD=26°

2DBC=72+26=98

∠DBC=98/2=49

∠ABD=72-49=23°

2) ∠MNК+∠KNP=140

∠MNК=140-∠KNP

∠MNK:∠KNP = 2/5=0,4

∠MNK=0,4∠KNP

0,4∠KNP=140 - ∠KNP

0,4∠KNP+∠KNP = 140

1,4∠KNP=140

∠KNP=140/1.4=100°

∠MNК=140 - 100=40 °