4x + 6x = 9x why is the answer 9x

Aword processing program requires a 7- digit registration code made up of the digits 1,2,4,5,6,7 and 9 each number has to be used and no number can be used mor than once how many codes are possible

What is always true about a positive integer raised to a negative odd power?

Using the figure below, select the two pairs of alternate interior angles. a: point 1 and point 4 b : point 2 and point 3 c: point 6 and point 6d: point 5 and point 7