How many neutrons does Chlorine-38 have if the isotope has a mass is 38?

The answer is either 21 or 22

Step-by-step explanation:

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the answer to the question is a  

it has the same slope and the same y-intercept.

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: