Answer:
As a reduced fraction: [tex]\frac{120}{5}[/tex] minutes, which is 24 minutes
Step-by-step explanation:
Sam's speed is 1 lawn in 40 minutes. Vanessa's speed is 1 lawn in 60 minutes. If they both work together, the total speed is:
[tex]\frac{1}{40}+\frac{1}{60}=\frac{1(3)}{40(3)}+\frac{1(2)}{60(2)}=\frac{3}{120}+\frac{2}{120}=\frac{5}{120}[/tex]
Which means that the total speed would be 5 lawns in 120 minutes. To find the time it would take to mow one lawn at that speed, we need to invert that speed so we get minutes per lawn:
[tex]\frac{120}{5}=24minutes[/tex]