Which choice is the common difference between the terms of this arithmetic sequence? 4x + 7y, 8x + 2y, 12x + -3y, 16x - 8y, 20x - 13y, a.4x - 5y b.-5x - 4y c.4x + 5y d.5x + 4y e.5x - 4y

Can someone check if i did this correct. it’s number 4 if you’re wondering.

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?

You eat $0.85 for every cup of hot chocolate you sell. how many cups do you need to sell to earn $55.25