Explanation:

The exponential formula for the required value of the half-life

t

1

/

2

of the given substance is:

A

=

A

0

(

1

2

)

t

t

1

/

2

, where,

A is the final amount of the given radioactive element.

A

0

is the initial amount of the given radioactive element.

t is the total time of decay.

The algebraic rule for the exponential equation for this problem is shown below:

a

m

=

a

n

→

m

=

n