5 x − n or t h am er i c a l b u tt er f l i es 3 x − so u t h am er i c an b u tt er f l i es 5 x = 30 ∣ d i v i d e b y 5 x = 6 3 x = 18 3 x − so u t h am er i c an b u tt er f l i es 2 x − e u ro p e an b u tt er f l i es 2 x = 2 ∗ 6 = 12 T h ere a re 12 e u ro p e an b u tt er f l i es an d 18 so u t h am er i c an b u tt er f l i es .
The number of South American butterflies is found by setting up the ratio 5/30 = 3/x, which gives 18 South American butterflies. The number of European butterflies is found by setting up the ratio 3/18 = 2/x, which gives 12 European butterflies. ;
There are 18 South American butterflies and 12 European butterflies in the butterfly park. This was determined using the ratios given for North American and South American butterflies, and then South American and European butterflies. The calculations followed step-by-step using the defined ratios and known quantities.
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