Answer:
Step-by-step explanation:
First lest us calculate the area of the rectangle
given that
length= 50ft
width= 40 ft
Area = length *width
Area= 50*40
Areaa= 2000 ft^2
given that 3/10 of the lawn is yet to be mowed
(3/10)*2000
0.3*2000= 600ft^2
Therefore the area that has been mowed is 2000-600= 1400 ft^2
1400 ft^2
since the direction of the mower is along the lenght of the lawn
area= lenght*width
1400= 50*width
width= 1400/50
width= 28 ft