Machine R can produce x units in 3/4 of the time it takes machine N to produce x units. Machine N can produce x units in 2/3 the time it takes machine O to produce x units. If all three machines are working simultaneously, what fraction of the total output is produced by machine N?	Choose the correct option:
A) 1/2	B) 1/3	C) 4/13	D) 8/29	E) 6/33
Let the following be true:   R makes x in time t   Then the following follows:   N makes x in 4t/3   O makes x in 3/2(4t/3) = 2t   M:N:O = 1:4/3:2=3:4:6   So N=4/(3+4+6)=4/13=4/13
<result>C</result>
Machine R can produce x units in 3/4 of the time it takes machine N to produce x units. Machine N can produce x units in 2/3 the time it takes machine O to produce x units. If all three machines are working simultaneously, what fraction of the total output is produced by machine N?