Question

已知4a=5b,求(a-b)/b,a/(a+b),(a+b)/b

Answer 1

已知：4a=5b

故：a=5b/4 b=4a/5

1) (a-b)/b

=(5b/4 - b) / b

=(1/4b) / b

=1/4

2) a/(a+b)

=a/(a+4a/5)

=a/ (9a/5)

=5/9

3) (a+b)/b

=(5b/4+b)/b

=(9b/4)/b

=9/4