point 39 centimeters is in an inch        cm x .39 = inches

So, inches divided by .39 = cm's.

Sorry, it = 2x-12    I tried to solve it, you need to simplify, not the same! this must be what you want!

4m/.01 = 400cm, A cm is .01 of a m (1 100th) so 4/.01=400

If you wanted meters from CM's 4cm X .01 = .04m     A meter is 100 cm's,  So 4/100 =.04

Think of metric like money, we have always had metric money A dime is point 10 dollar  a  penny is point 100 of a dollar So a penny is .01 of a dollar!

2r x pi = C,   2r because radius is 1/2 diameter, then dia times pi = cir.

2x2 = 4 x 3.14159 =12.566 

5x(7x-4y) ,=  5x(7x)+5x(-4y) ,=  5x * 7* +5x(-4y) ,=  35x(squared) + 5x(-4y) ,=  35x" - 20xy.

so,  35x squared - 20xy      is answer.

pi = 1.314159265_________ goes forever, is close to but not equal 22/7 = 3.142857142

pi is the ratio of a circle's circumference to its diameter.

(5x-3)-(3x+9) the parenthesis are not required, 5x-3-3x+9, like terms 5x-3x=2x, like terms -3+9=6,

So answer is 2x+6.

Remeber if there was no sign between ()and() this would be a different deal as it would involve multiplying the polynomials.

(5x-3)-(3x+9)  remove parethesis, not related to problem

5x-3-3x+9 5x and 3x are like terms, so 5x-3x = 2x  and

 -3+9 = 6 are  like terms so,  2x+6 is the answer. Without a value for x this cannot, be further simplified. look between paranthesis! or you'll need FOIL First Out Inside Last  (5x-3)(-3x+9), = (5x * -3x + 5x * 9 - 3 * -3x - 3 *9)

Then solve all like terms to get ( -15x squared +54x - 27)