With two reapers operating, a field can be harvested in 1 h. If only the newer reaper is used, the crop can be harvested in 1.5 h. How long would it take to harvest the field using only the older reaper?

x three hours

Step-by-step explanation:

With two reapers a field can be harvested in 1 hour

Operating only the newer reaper crop can be harvested in 1,5 hour (3/2), then in one hour it does 1 / (3/2) = 2/3

Let call x number of hours the older reaper, take doing the job, then

In 1 hour time the older reaper does 1 / x

Then according to problem statement

As with two reapers the field can harvested in one hour

1 / x + 2/3 = 1 ⇒ (3 + 2*x) / 3*x = 1

3 + 2*x = 3*x

- 3*x + 2*x = - 3

- x = - 3

x = 3