1) (-17+23)*(-5)= 6*(-5) = -30
2)1/2 +x =3/4 aducem la acelasi numitor
2+4x=3
4x=3-2
4x=1
x=1/4
3)0,(6)=6/9=2/3
ma=(a+b)/2=2/3
a+b=2*2/3
a+b=4/3
ab=24
4)ΔABC, mas<A=90
x-masura unui < ascutit
x/2 -masura celuilalt < ascutitunghic
x+x/2=90 aducem la acelasi numitor
2x+x=180
3x=180
x=60 grade
x/2=30 grade
5)a,b,c, ip cu 2,3,5
2a=3b=5c=k
a=k/2
b=k/3
c=k/5
a+b+c=62
k/2 +k/3 +k/5 =62 aducem la acelasi numitor
15k+ 10k+6k= 1860
31k=1860
k=60
a=60/2=30
b=60/3=20
c=60/5=12