Explanation:
1.
$4 for 8 days. that means $4 on each and every day, 8 times.
so, in total that is 4 × 8 = $32
that is how multiplications work.
m×n means that m is added n times (or vice versa and n is added m times).
2.
similar here.
$25 each time the customer missed a payment. and he missed 4 times that year.
the bank returned the fees for all 4 occasions. so,
returned money = 25 × 4 = $100