Question

a+b+c= 180
a=c:2
a=b-20

Answer 1

a = c : 2 ⇒ c = 2 a

a + b + 2a = 180 ⇒ 3a + b = 180
Avem sistemul de ecuatii cu doua necunoscute:
3a + b = 180 
a = b - 20
deci: 3(b - 20) + b = 180
3b - 60 + b = 180
4b = 180 + 60
4b = 240
b = 60

a = b -20
a = 60 -20
a = 40

a = c: 2
c = 2a
c =2· 40
c = 80

proba: a + b + c = 180
60 + 40 + 80 = 180
180 =180