Question

Numerele a,b si c sunt direct proportionale cu 4, 5, respectiv 7. Aflati numerele a, b si c stiind ca 3a+c=285

Answer 1

{a,b,c} d.p. {4,5,7}
a:4=b:5=c:7=k
a=4k
b=5k
c=7k
3a+c=285
3•4k+7k=285
12k+7k=285
19k=285/19
k=15
a=4•15
a=60
b=5•15
b=75
c=7•15
c=105