the cost for a certain company producing items is C=50x+200 and the revenue function for selling items is R=-0.5(x-120)^2+7200, the maximum capacity of the company is 150 items. what is the profit for producing 70 items? what is the profit for producing 80 items? Stuck need to explain

/is used for a fraction 1) if x = 2/3 and y = 3/4, what is the value of (x + y) (x/y) expressed as a common fraction? 2) what is the least positive integer greater than 1 that leaves a remainder of 1 when divided by each of 2, 3, 4, 5, 6, 7, 8, and 9? 3) the ponde family's powerjet pumps 420 gallons of water per hour. at this rate, how many gallons of water will it pump in 45 minutes? 4) kim's insurance company pays 80% of the cost of all prescription medication she purchases in a year beyond the first $250 worth of prescriptions. her prescriptions for this year cost a total of $570. how many dollars of this amounts will kim's insurance company pay?

Pls! does anybody know a shortcut for answering these types of questions in the future?

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