7) a+249<256
a<256-249
a<7
a={0,1,2,3,4.5,6}
b-625<8
b<625+8
625<b<633
b={625,626,627,628,...632}
18-c<13
18-13<c
5<c
18>c>5
c={6,7,8,9,10,...17}
10) notam numarul cu a
(a+139)-425+99=571
(a+139)-425=571-99
(a+139)-425=472
a+139=472+425
a+139=897
a=897-139
a=758
