Răspuns :
a(a+1)(a+2)=a(a+1)+180
a()()-a()=180
a()()=180
(axa+a)()=180
axaxa+axa+axa+a=180
a(axa+a+a+1)=180
a(axa+2a+1)=180
a(a+1)(a+1)=180
a=5
a()()-a()=180
a()()=180
(axa+a)()=180
axaxa+axa+axa+a=180
a(axa+a+a+1)=180
a(axa+2a+1)=180
a(a+1)(a+1)=180
a=5