Please confirm if I did this correctly:

What is the Principal?
Principal $21250
X 10%
2,125
What is the total amount paid by the consumer?
2,125
x 3.5 years
7,437.5
+21,250.0
28,687.50

What is your question?

From the disconnected pieces of arithmetic , are we finding the amount due after 3/5 years at simple interest of 10% on a loan of $21250 ?

That would be 21250 + (.1)(3.5)(21250) = 28687.50

Very unusual to have "simple interest" on a time longer than 1 year. Compound interest would be the norm