Parakeets 80471

Mr. Spacek keeps birds. It has more than 50 and less than 100. Parakeets make up a ninth and canaries a quarter of the total. How many birds did he keep?

Correct answer:

n =  72

Step-by-step explanation:

$$\begin{gathered} 50<n<100 \\ 9=3^2 \\ 4=2^2 \\ LCM(9,4)=2^2\cdot 3^2=36 \\ x=LCM(9,4)=36 \\ x<50 \\ 50<2x<100 \\ 3x>100 \\ n=2\cdot x=2\cdot 36=72 \end{gathered}$$

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