Two tractors can plow a field in 15 hours. If the productivity of the first tractor was twice as much as in reality

Two tractors can plow a field in 15 hours. If the productivity of the first tractor was twice as much as in reality, and the productivity of the second was 20% more than in reality, then both tractors would need 10 hours to plow the same field. How many hours every tractor can plow this field, working alone.

1. Both tractors will plow the field in: T = 15 hours;
2. The first tractor will plow the field in: T1 hours;
3. The second tractor will need time: T2 hours;
4. We compose the equation of plowing in terms of tractor performance:
P1 + P2 = 1 / T = 1/15 (1 / day);
P2 = 1/15 – P1;
2 * P1 + 1.2 * P2 = 1 / To = 1/10;
2 * P1 + 1.2 * (1/15 – P1) = 1/10;
0.8 * P1 = 1/50;
P1 = (1/50) / 0.8 = 1/40 (1 / hour);
P2 = 1/15 – P1 = 1/15 – 1/40 = 1/24;
T1 = 1 / P1 = 1 / (1/40) = 40 hours;
T2 = 1 / P2 = 1 / (1/24) = 24 hours.
Answer: the first tractor will plow the field in 40 hours, the second in 24 hours.