(c) Go through option. Consider choice (c).
Efficiency of first worker = 5%
Efficiency of second worker = 4%
∴ In 7 hours first worker completed 35% work
In 5 hours second worker completed 20% work
Thus, work completed = 55%
Remaining work = 45%
Hence, one condition is satisfied.
Again, first worker will take 9 more hours to complete 45% work
[=9]Thus, first person completes 7 × 5 + 9 × 5 = 80% work
and second person completes 5 × 4 = 20% work
Hence, second condition is also satisfied.