The following information is related to the selling and administrative costs. S&A cost pool includes depreciation (fixed, 24000 dollars per month, commissions (variable, 10 dollars per unit) and wages of managers and supervisors (semi-variable). During the last six months, the highest activity level was in March (28000 units produced) and total MOH cost was $980000. The lowest activity level was in January (23000 units produced) and total MOH cost was $880000. a.) Write the cost formula of wages (use the high-low method). b.) Estimate Total S&A Cost for July (23500 units produced) by using the data of the year's first six months.