Please can someone help me math!!?

Question

A farmer wants to put fence around a rectangular field. If the dimensions of the field are 200 feet by 400 feet, and fencing costs $1.35 per foot, how much will it cost to fence in the entire field?

 $600 

$810 

$1200 
$1620

Answer 1

 Dimensions of the rectangular field  l= 400 and b= 200

 Area of the rectangular field    2(l+b)

                                             =  2 ( 400 + 200 )

                                             =  2 (600)

                                             = 1200 feet

 The total cost to fence the rectangular field is   1200 × 1.35

                                                                           = $ 1620