Question

Plz toate Exercițiile daca se poate !!! Plz !!!

Answer 1

1.
27, 29,31...3 nr impare
2.
12*210=2520
3.
10*13-23=130-23=107
4.
l=5 cm
L=3*5= 15 cm
P= 2l+2L=2*5+2*15=10+30=40cm
5.
3kg.........6 lei
5 kg........x lei

x= 5*6 :3= 30:3=10lei.

II.
1)
(3x-5):4+(275-2*30):5=53
(3x-5):4+(275-60):5=53
(3x-5):4+215:5=53
(3x-5):4+43=53
(3x-5):4=53-43
(3x-5):4=10
3x-5=4*10
3x-5=40
3x=40+5
3x=45
x=45:3
x=15

2.
a=1543-721+312-200-900
a=34

b=60-(54-27):3=60-27:3=60-9=51

3a : 2b= 3*34 : 2*51=102 : 102=1

3)
a+b+c=81
b=2a+3
c=15
a=?
b=?

a+2a+3+15=81
3a+18=81
3a=81-18
3a=63
a=21

b=2*21+3
b=45

verific: 21+45+15=81

4)
l=1/3*L
P=80cm

L/3=l
2l+2L=80
2*L/3+2L=80
2L+6L=80*3
8L=80*3
L=30cm
l=30:3
l=10cm