Question 1139209
You mean, "twice the speed of" or "twice as fast as", to be included in the first part of the description.


C has plowing speed  x hectares per hour
B has speed 2x hectares per hour
A has speed 4x hectares per hour


{{{highlight_green((4x+2x+x)*3=8)}}}

-

{{{3*7x=8}}}

{{{x=8/21}}}

<pre>
TRACTOR        PLOW RATE, hectares per hours
A              {{{32/21}}}
B              {{{16/21}}}
C              {{{8/21}}}
</pre>


Time for tractor A to plow 10 hectares?
{{{(32/21)*t=10}}}

{{{t=10(21/32)}}}

{{{t=5(21/16)}}}

{{{highlight_green(t=105/16)}}}
6 hours 34 minutes, tractor A alone, 10 hectares