Write an equation to find how long it will take for the mass of the radioactive substance to reach 27grams.

were are the answer choices

Using the expression found earlier, set up an equation:

64(0.75)^x = 27

Divide both sides of the equation by the initial amount and rewrite the decimal number as a fraction:

64(0.75)^x=27           = 27/64

           64

(3/4)^x = 3^3

              4^3

Rewrite the bases to be equal:

(3/4)^x = 3^3

               4^3

Using the properties of exponents, rewrite the second term:

(3/4)^x = (3/4)^3

Since the bases are equal, set the exponents equal to each other:

x = 3

This means after 3 hours, Dr. Steve will have 27 grams of the radioactive substance left.

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step-by-step explanation:

i took the test: )

i got 10.28 but that rounds up to 10.3