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If a certain machine produces x units every 15 minutes
and another machine produces y units every 30 minutes,
how many units will both machines working together produce in z hours?
a) z(15x+30y)
b) 2z(2x+y)
c) 60z(4x+2y)
d) 60z(x/4+y/z)
e) z/(4x+2y)
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If a certain machine produces x units every 15 minutes, it produces 4x units every hour.
If another machine produces y units every 30 minutes, it produces 2y units every hour.
Working together, both machines produce 4x+2y units every hour.
Working together, both machines produce z*(4x + 2y) = 2z*(2x+y) units in z hour.
ANSWER. Option (b).
Solved.