How many solutions are there to the system of equations shown? {16x−12y=40
4x−3y=10

I don't really understand these so an explanation would be nice :)

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%