Question

afla nr necunoscut :450-12×a=330; 1000-a:5=965; 935-a+72×12=1500; 170-(18+2×a):5=10; (320+a)×3×5=7500

Answer 1

450-12xa=330
12xa=450-330
12xa=120
a=120:12
a=10

1000-a:5=965
a:5=1000-965
a:5=35
a=35x5
a=175

935-a+72x12=1500
935-a+864=1500
935-a=1500-864
935-a=636
a=935-636
a=299

170-(18+2xa):5=10
170-(18+2xa)=10x5
170-(18+2xa)=60
18+2xa=170-60
18+2xa=110
2xa=110-18
2xa=82
a=82:2
a=41

(320+a)x3x5=7500
(320+a)x15=7500
320+a=7500:15
320+a=500
a=500-320
a=180