Need (in attachment) i have no idea what to do.

If the average of x,y and z is 15 what is their sum

Harold took five different samples of thirty-five randomly selected students from the 520 students he surveyed. the means of the samples are shown below. sample mean sample 1: 3.4 sample 2: 3.2 sample 3: 4.1 sample 4: 4.6 sample 5: 3.1 the predicted mean of the population will fall between 3.1 and ?

The equation of line ab is y = 2x + 4. write an equation of a line parallel to line ab in slope-intercept form that contains point (3, −2). (4 points) y = 2x + 4 y = negative 1 over 2 x − 1 over 2 y = − 1 over 2 x − 7 over 2 y = 2x − 8