Question

afla numerele necunoscute (100-b:3)×5=490
(c:9:3)×4=20

Answer 1

(100-b/3)×5=490

500-5b/3=490

3×500-3×5b/3=3×490

1500-5b=1470

-5b=1470-1500

-5b=-30

b=6

(c/9×1/3)×4=20

c/27×4=20

4c/27=20

4c=540

c=135

Answer 2

primul
(100-b:3)×5=490
a
a×5=490
a=490:5
a=98
100-b:3=98
b:3=100+98
b:3=198
b=198:3
b=66

al doilea
(c:9:3)×4=20
d
d×4=20
d=20:4
d=5
c:9:3=5
c:9=5×3
c:9=15
c=9×15
c=135
SPER CĂ TEAM AJUTAT!!!