13h/0.5mi. = 26 h/mi. with new machine.
d1 = 2h * 1mi/26h = 2/26= 1/13 Mi. by new machine.
d2 = 13/26 - 2/26 = 11/26 mi. remaining.
15h/0.5mi. = 30 h/mi. with old
machine.
T = (11/26)mi * 30h/mi = 12.69 h.
A new machine that deposits cement for a road requires 13 hours to complete a one-half mile section of road. An older machine requires 15 hours to pave the same amount of road. After depositing cement for 2 hours, the new machine develops a mechanical problem and quits working. The older machine is brought into place and continues the job. How long does it take the older machine to complete the job
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