Answer:
30
Step-by-step explanation:
Let number of tetras be "t"
number of guppies be "g"
number of minnows be "m"
Ratio of tetras to guppies is 4:2, or reducing, 2:1. Thus we can write:
[tex]\frac{t}{g}=\frac{2}{1}\\t=2g[/tex]
Ratio of minnows to guppies is 1:3, so we can write:
[tex]\frac{m}{g}=\frac{1}{3}\\g=3m[/tex]
or, m = g/3
Also, total there are 60 fish, so we can write:
t + g + m = 60
or
2g + g + g/3 = 60
Solving this, we can solve for g. Shown below:
[tex]2g+g+\frac{g}{3}=60\\3g+\frac{g}{3}=60\\\frac{9g+g}{3}=60\\10g=180\\g=18[/tex]
Now, finding t and m:
m = g/3 = 18/3 = 6
m = 6
and
t = 2g
t = 2(18)
t= 36
There are 36 tetras and 6 minnows. So, there are
36 - 6 = 30 more tetras than minnows
