Question

Numerele rationale pozitive a,b,c sunt direct proportionale cu 3, 7, respectiv 8 iar 8a+7b+3c=485.
a)Aflati numerele a,b ,c .
b)Rezolvati ecuatia ax+b=c , unde a,b,c sunt determinate mai inainte.

Answer 1

a=3k
b=7k
c=8k

24k+49k+24k=485
97k=485
k=5

a=5*3
a=15

b=7*5
b=35

c=8*5
c=40

ax+b=c
15x+35=40
15x=40-35
15x=5
x=5/15
x=1/3

Answer 2

a)  a/3=b/7=c/8=k     a=3k  b=7k   c=8k
8a+7b+3c=485
24k+49k+24k=485       97k=485      k=5
a=15
b=35
c=40
b)    15x+35=40
    15x=5    x=1/3