Tobey can mow a lawn in 50 minutes. Working together, Tobey and Nick take only 30 minutes to mow the same lawn. How long would it take Nick to mow the lawn alone?

Tobey=1/50 lawn per minute

tobey+nick=1/30 per minute

so therefor

1/50+nick=1/30

nick=1/30-1/50

nick=5/150-3/150

nick=2/150

nick=2/150 lawn per minute

so

2/150 tiems what=1

times 150/2 both sideds

what=75

75 mins