if the coefficients of 1/x and x^2 are equal in the expression of (ax - b/x^2 )^8 find the relationship between a and b

In stepmber, daniel and justin opened a business. during their first three months of business, their average monthly profit was $51. if during their first month, they lost $29, and during their second month, they gained $115, what was their profit or loss for their third plzzz i will give you 299 points