a is 1.5 times as fast as b. a alone can do the work in 20 days. if a and b working together, in how many days will the work be completed? Choose the correct choice from the following options:
A) 23	B) 22	C) 12	D) 24	E) 25
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) / 1.5</gadget>
<output>0.033333</output>

<gadget id="calculator">(1/20) + 0.033333</gadget>
<output>0.083333</output>

<gadget id="calculator">1 / 0.083333</gadget>
<output>12.000048</output>

<result>C</result>
a is 1.5 times as fast as b. a alone can do the work in 20 days. if a and b working together, in how many days will the work be completed?
divide(const_1, add(divide(const_1, 20), divide(divide(const_1, 20), 1.5)))
a can finish 1 work in 20 days b can finish 1 / 1.5 work in 20 days - since a is 1.5 faster than b this means b can finish 1 work in 20 * 1.5 days = 30 days now using the awesome gmat formula when two machines work together they can finish the job in = ab / ( a + b ) = 20 * 30 / ( 20 + 30 ) = 20 * 30 / 50 = 12 days so answer is c