If you want to earn 15% annual simple interest on an investment, how much should you pay for a note that will be worth $27,000 in 10 months?

For some payment P, you want
  27000 = P + I
  27000 = P + Prt . . . . substituting the formula for I
  27000 = P(1 + .15·10/12) = 1.125
Then
  27000/1.125 = P = 24000

You should pay $24,000 for the note.

the law of definite proportions states samples of a compound will always contain the same proportion of elements by mass. in other words, a given compound will always contain the same elements in the same proportions by mass.the law of multiple proportions states when two elements combine with each other to form more than one compound, then the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.