Write the fraction as

1/[(5 √5)x - (3√ 3)y]

Multiply numerator and denominator by [(5 √5)x + (3√ 3)y].

Using the difference of squares formula, the denominator becomes [(5 √5)x]² - [(3√ 3)y]² = 125x² - 27y²

so

A = [(5 √5)x + (3√ 3)y] and B = 125x² - 27y².

is this true?