Question 37114
if you think about things like this as speed = quantity/time: here the quantity is the lawn area mowed. Lets call this A for area.


So, Jane: Jane's speed = A/3
and Lester: Lester's speed = A/4


together we have still the same Area of lawn in some time, t:
Jane + Lester speed = A/t
{{{ A/3 + A/4 = A/t }}}


all terms have an A, co we can cancel:
{{{ 1/3 + 1/4 = 1/t }}}
{{{ 1/t = 4/12 + 3/12 }}}
{{{ 1/t = 7/12 }}}
{{{ t = 12/7 }}} hours


which is nearly 2 hours. This makes sense --> together it would take an even quicker time.


jon.