To find Simon's maximum amount he can borrow against his home you will use the Home Loan Value Formula.
Home is worth: $400,000
Remaining balance: $175,000
Borrow: up to 75% on home
First, you'll want to take the market value of $400,000 and multiply it by 75% (.75) which gives you $300,000.
Then, you'll need to subtract what Simon owes on the home to find the amount he can borrow.
$300,000 - $175,000 = $125,000
Simon can borrow $125,000 against his home.