ex 13. 2a+3a=85
5a=85
a=85:5=17
ex.14 a-29=52 a=52+29= 81
ex 15 punctul b (x+3)(y-2)=9x2 x+3=9 x=6 y-2=2 y=4
(x+3)(y-2)=18x1 x+3=18 x=15 y-2=1 y=3
(x+3)(y-2)=6x3 x+3=6 x=3 y-2=3 y=5
ex 16 a) 8x(a+b)+x=93 8x11+x=93 x=93-88=5
b)5x+4a+3b=85-2b-a
5x+4a+3b+2b+a=85
5x+5a+5b=85
5x+5x(a+b)=85
5x+ 5x11=85 5x=85-55 5x=30 x=6
