Solve, using the substitution method.
j + k = 3
j – k = 7

To use the substitution method, you first need to set j or k = to something else like this. j+k=3   subtract k from both sides to get j=3-k

Now use the second equation and substitute 3-k where j is like this.  3-k-k=7

3-2k=7 subtract 3 from both sides to get -2k=4

divide both sides by -2 to get k=-2

now use -2 for k and solve for j in either equation and you will get. j=5

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: