Please help with this answer its 3/7 times 8

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

Rewrite the following quadratic functions in intercept or factored form. show your work. y = x^2 + 7x + 10

1. according to the internal revenue service, the mean tax refund for the year 2007 was $2,708. assume the standard deviation is $650 and that the amounts refunded follow a normal probability distribution. a. what percent of the refunds are more than $3,000? b. what percent of the refunds are more than $3,000 but less than $4,000? c. what percent of the refunds are less than $2,000?