Question

numerele a b si c sunt invers proportionale cu 3 4 si 5. determinati valoarea raportului (3a+2b+5c)/(a+b)

Answer 1

3a=4b=5c     b=3a/4    c=3a/5
(3a+2b+3c)/(a+b)=
=(3a+2×3a/4+3×3a/5)/(a+3a/4)=
=(3a+3a/2+9a/5)/(a+3a/4)=          se simplifica cu a
=(3+3/2+9/5)/(1+3/4)=
=[(30+15+18)/10]  / (7/4)=
=63/10 ×4/7=
=18/5