Let t represent Todd's age now.
.. 4(t -3) -(t -3) = 81 . . . . . . 3 years ago, their differnce in ages was 81.
.. 3t -9 = 81
.. t = (81 +9)/3 = 30
Todd is 30 now.
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You can also work this by considering "ratio units." 3 years ago, the ratio of their ages was 4:1, a difference of 3. That difference corresponds to 81 years, so each "ratio unit" represents 81/3 = 27 years. Todd's age then was 1 ratio unit, 27 years. Now, Todd's age is 30.
        
             
        
        
        

Step-by-step explanation:
find the value of the constant of proportionality k 

c =total cost
d =days
 
        
             
        
        
        
Answer:
your answer is 211.23949776785489 milligrams 
Step-by-step explanation:
i hope this helps 
have a nice day/night
mark brainiest please :)
 
        
             
        
        
        
Answer:
An infinite number of solutions 
Step-by-step explanation:
This is because of all the 0's the zeros represent none and none is infinite. When in the matrix you are solving and solving is a infinite. When times 0 is 0 and when divided by 0 is infinite so an infinite amount of answers.