If a : b = 2 :5 and b : c = 5 : 3 then (a + c) : c = ?

Answer 1

from ur fist ratio,
2b = 5a ; means a = 2b/5
from the second,
5c = 3b ; means c = 3b/5
now, a+c = 2b/5 + 3b/5
a+c = b
hence (a+c):c is again b:c = 5:3

Answer 2

a:b = 2:5 means that

a = 2 and b = 5

b:c = 5:3 means that

b=5 and c = 3

(a + c) = (2 + 5) = 7

c = 3

Therefore, (a + c) : c = 7:3

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Adding to this after reading the other person's answer....

Gosh, I don't know who's right now. They both make sense to me... :-|