What set of numbers includes square roots of negative numbers?

1. what expression would be the same as 6x+x+0 2. find the prime factorization of 60 3. write the expression for 6 + x in words.

Can some one me with these questions

In a certain city, the hourly wage of workers on temporary employment contracts is normally distributed. the mean is $15 and the standard deviation is $3. what percentage of temporary workers earn less than $12 per hour? a. 6% b. 16% c. 26% d. 36%