Find the largest 3 digit number, with no two digits the same and with its digits in ascending order, which when multiplied by 5 has its digits in descending order?

To represent the number in ascending order, we can use the variables x,y and z to represent separate digits. IN this case, in ascending order, the formula is x + 10 y + 100 z. On the other hand, the descending order is z + 10y + 100x. The expression then becomes (x + 10 y + 100 z)*5 = z + 10y + 100x. The other functions are x and z should be greater than 1 to 9 while y allows zero.