What is the direct linear variation equation for the relationship?

y varies directly with x and y=4 when x=12

a. y= x

b. y=3x

c. y=x+8

d. y=x-8

An office supply company conducted a survey before marketing a new paper shredder designed for home use. in the survey, 80 % of the people who tried the shredder were satisfied with it. because of this high satisfaction rate, the company decided to market the new shredder. assume that 80 % of all people are satisfied with this shredder. during a certain month, 100 customers bought this shredder. find the probability that of these 100 customers, the number who are satisfied is 69 or fewer.

The sum of the squares of two numbers is 8 . the product of the two numbers is 4. find the numbers.

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?