How to write expression for The product of ten less than a number and the number

Find the quotient. 50a2 – 98b2 -5a +7b

Bring the fraction a/a-4 to a denominator of 16-a^2

Many newspapers carry a certain puzzle in which the reader must unscramble letters to form words. how many ways can the letters of emdangl be arranged? identify the correct unscrambling, then determine the probability of getting that result by randomly selecting one arrangement of the given letters.