If p varies directly as r and p=4,r=2,what the value of r when p=12

r = 6

Step-by-step explanation:

Given that p varies directly as r, then the equation relating them is

p = kr ← k is the constant of variation

To find k use the condition p = 4, r = 2

k = = = 2

p = 2r ← equation of variation

When p = 12

12 = 2r ( divide both sides by 2 )

hence r = 6

a) y = -3x +2

b) y = 1/2x -6

these 2 can be combined into one equation.

-3x +2 = .5x -6

8 = 3.5x

x = 8 / 3.5 = 2.2857142857

y = -3 * (8 / 3.5) +2

y = (-24 / 3.5) + 2

y = -4.8571428571

step-by-step explanation:

the 8 in 8,420 is in the thousands place so it's value is 8 thousand.

the 8 in 6,870 is in the hundreds place so it's value is 8 hundred.

divide 8000 by 800 to find the answer:

8000 / 800 = 10

the 8 in 8,420 is 10 times greater than the 8 in 6,870