Five continuous natural numbers, the smallest number is 4 / 5 of the largest number, then what is the smallest number

Five continuous natural numbers, the smallest number is 4 / 5 of the largest number, then what is the smallest number

Hello Zhang Xiaorong, 2010
Let X be the minimum and X + 4 be the minimum
X÷(X+4)=4/5
5X=4X+16
X=16