Mrs. and mr hill purchased a detached home for $1,200,000 with a down payment of 25%. for the remainder, they signed a mortgage contract with BMO at 6.25% compounded semi annually (fixed rate for 5 years) and monthly payments for 25 years.

suppose they decided to pay an extra 10% of the original mortgage loan after 3 years. how much interest would this save over the life of the mortgage?