Richard can mow the lawn three times as fast as Terri. Together, they finish mowing the lawn in 20 minutes. Which of the following equations would describe how many minutes it would take Richard to mow the lawn by himself? a. 1/x+1/3x=1/20 b. 1/x+1/3=1/20 c. 20 (1/x+1/3x)=1/20 d. x+3x=1

d it adds the two up and only mutiplys terris amount.

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:

to find the total number of combinations, multiply the quantity of each item by each other:

2 pairs of shoes x 3 pairs of shorts = 6 different combinations.