Răspuns:
Explicație pas cu pas:
[tex]\dfrac{a}{b} =\dfrac{2}{5} ~=>~\dfrac{a}{2} =\dfrac{b}{5} =k,~=>~a=2k,~b=5k.\\\dfrac{7a-2b}{4a+3b}=\dfrac{7*2k-2*5k}{4*2k+3*5k}=\dfrac{4k}{23k} =\dfrac{4}{23} .[/tex]
4/23
altfel de rezolvare
imparti cu b≠0 toata relatia
(7a/b-2b/b)/(4a/b+3b/b)=
=(7*2/5-2)/(4*2/5+3)
=((14-10)/5))/((8+15)/5)
=(4/5)/(23/5)=
=4/23
