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Step-by-step explanation:

f-  -3u=21 divide each side by (-3)

-3u/-3=-21/3

u=-7

g) 23+a=12  use subtraction method , subtract 23 from both sides

23-23+a=12-23

a=-11

h) -9+b=15  use additional method, add 9 to both sides

-9+9+b=15+9

b=26

amount of oatypop that contains the prize = 40%

amount   of oatypop which doesn't contain the prize = (100-40)=60%

probability that hannah will win a prize

    = s +f s +f f s+ff   f s+ff f f s+ infinity.where f= failure,s= success

=   or 60%

probability that hannah only has to buy 3 or less boxes before getting a prize= (s) and ( f s) and (ff s) and (f f f s)

        = = 87.04 %  

step-by-step explanation: