Two lines in intersecting planes are skew

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

The measures of the legs of a right triangle are 15m and 20m . what is the length of the hypotenuse

When i'm with my factor 5, my prodect is 20 .when i'm with my addend 6' my sum is 10.what number am i