Question

a field has a perimeter of 1.48 kilometers it is 460 meteres long how wide is the field

Answer 1

280 meters wide. 
Step 1: Convert kilometers to meters. 1.48=1480
Step 2: Multiply the side length that you have by 2. 2x460=920
Step 3: Subtract 920 from 1480. 1480-920=560.
Step 4: Divide 560 by 2. 560/2=280
There is your answer! 

Answer 2

1.48 km = 1480 m =2*460+2*w

2*w=1480 - 2*460=560
w=560:2=280 meters wide