Two different schools (A and B) have the same number of pupils. The ratio of the boys in school A and the boys in school B is 2:1 and the ratio of the girls in school A and the girls in school B is 4:5. Find the ratio of the boys in school A to the girls in school A.
Given that, `"a"/"c"` = `"2"/"1"`
`"b"/"d"` = `"4"/"5"`
`"a"+"b"` = `"c"+"d"`
we want to find a/b
a = 2c
5b = 4d
a-c = d-b
a-(`"a"/"2"`) = (`"5b"/"4"`)-b
`"a"/"2"` = `"b"/"4"`
`"a"/"b"` = `"2"/"4"` = `"1"/"2"`
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