Blaine had $68 in his checking account. he tried buying a coat, but he couldn't make the purchase because the money in his account was $21 short of the price of the cost how much did that coat cost?

Blaine had $68, but he needs $21 more in order to be able to purchase the coat.  To find how much the coat costs, you just need to add how much money Blaine had to the amount he was missing.

$68 + $21 = $89

Therefore, the coat costs $89.