A. The equation that represents how much money Jane will have in total after saving for \( d \) days is:
\[ J(d) = 100 + 5d \]
B. The equation that represents how much money Ellis will have in total after saving for \( d \) days is:
\[ E(d) = 75 + 7d \]
C. To find out how many days it will take for Jane and Ellis to have the same amount of money saved, set their equations equal to each other:
\[ 100 + 5d = 75 + 7d \]
D. After solving the equation from part C to find \( d \), we can substitute that value back into either equation to find how much they will have saved. After solving, we find \( d = 25 \). To find how much Jane and Ellis will each have saved, we substitute \( d = 25 \):
\[ J(25) = 100 + 5(25) = 100 + 125 = 225 \]
\[ E(25) = 75 + 7(25) = 75 + 175 = 250 \]
So, after 25 days, Jane will have $225 and Ellis will have $250.