Can somebody me with questions 6-9 plsss

Suppose that a households monthly water bill (in dollars) is a linear function of the amount of water the household uses (in hundreds of cubic feet, hcf). when graphed, the function gives a line with slope of 1.65. if the monthly cost for 13 hcf is $46.10 what is the monthly cost for 19 hcf?

Present age of man is 45 years, 5 years back his age was 4 times age of his son what is present age of his son?

Let x = a + bi and y = c + di and z = f + gi. which statements are true?