Question

Probleme de clasa a patra

Answer 1

152.
a=5b
c=(5b+b):3=2b
5b+2b+b=80
b=80:8
b=10 bomboane
a=10×5=50 bomboane
c=(10+50):3=20 bomboane

153.
3d-2s=diferenta
3d+2s=50
50:5=10
d=3×10=30
s=2×10=20

3/3-2/3=1/3
3/3+2/3=50
1/3=50:5=10
d=10×3=30
s=10×2=20

verificare:
30-20=10(30:3)
30+20=50

154.
b=3a
c=4a
a+3a+4a=8a
8a=56
a=56:8
a=7
b=7×3=21
c=7×4=28

c-b=28-21=7

155.
a+b+c=45
c=(a+b)/2
b-a=a/2
b=a/2+a
b=3a/2
c=(a+3a/2)/2=5a/4
inlocuim in prima suma
a+3a/2+5a/4=45
4a+6a+5a=180
15a=180
3a=36
a=12
b=18
c=15

156.
a-b=14
a=3b
3-b=14
2b=14
b=7
a=3×7=21