(b) "if x > 0 and y > 0 then xy > 0" where x, y are real numbers.

Step-by-step explanation:

We know that multiplication product of two given positive real number will always be positive real number and if one of the real number is negative, the multiplication product will always be negative.

so for the given condition, if and , and are both positive real numbers

hence their multiplication product will also be a positive number.

∴

then, the surface area of the sphere shown in the image is: 256π sq. units!

step-by-step explanation:

the lateral surface area of a sphere is 2πrh where h=2r.

then:

surface area = 4πr^2.

in this case, r=8 units ⇒ surface area = 4π(8 units)^2. = 256π sq. units!

then, the surface area of the sphere shown in the image is: 256π sq. units!

the ratio of balloons to tables is 5: 2 and the constant variation is 5.

the equation is y=5x