If y is directly proportional to x, and y = 56 when x = 6, what is the value of x when y = 84?
A)6
B)9
C)13
D)15

B) 9

Step-by-step explanation:

According to the statement, we have the following relationship:

(Eq. 1)

Where:

- Proportionality constant, dimensionless.

- Independent variable, dimensionless.

- Dependent variable, dimensionless.

Such constant is eliminated by constructing this relationship:

(Eq. 2)

If we know that , and , then the value of is:

Hence, the correct answer is B.

second option

step-by-step explanation:

the measures of a triangle equal 180. use that to find x.

2x+3x+4x=180

9x=180

9x/9=180/9

x=20

now you know x, you know angle a is 40°, angle b is 60°, angle c is 80°.

because angle a is 40°, the first option doesn't work.

because angle b is 60°, the second option does work.

when you add angle a and b, you get 100°. complementary means it equals 90°, so the third option doesn't work.

when you add angle a and c, you get 120°, which is not 100.