It takes john 4 times as long as it takes jessica to mow a lawn. if it took them both 11 hours to mow the lawn, how long would it take john to mow the lawn alone?

If you would like to know how long would it take John to mow the lawn alone, you can calculate this using the following steps:

hours (Jessica) ... a
hours (John) ... b = ?
a + b = 11
b = 4 * a

a + b = 11
a + 4 * a = 11
5 * a = 11    /5
a = 11/5 = 2 1/5 = 2.2 hours

b = 4 * a = 4 * 2.2 = 8.8 hours

The correct result would be 8.8 hours.