If the price of a lawnmower was $1800 a year ago, 2/5 less than the cost right now, then it now costs 2/5*1800 = $720 more to buy one lawnmower.
The total cost of buying one lawnmower right now is $1800+$720 = $<<1800+720=2520>>2520
To purchase 4 such lawnmowers, Mr. Lucian will have to pay $2520*4 = $<<2520*4=10080>>10080
#### 10080