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Car park A would be cheaper till the 5th hour as we add 50 pennies every time so we start with 80 add 50 we get 130 and we keep adding until we get the fifth hour which is 280 we can make a formula out of this X will be the starting amount and then we keep adding the price of the car park so in car park a's case we add 50 so we get X+50 now we work the hours the hour can be Y so we get Y+1=X+50 then we can work out the hours to price for car park B which will be Y+1=X+30 then we solve it so X equals 80 in the car park A so +50 every hour and as for the second car park we get 150 in the first hour and then every hour we add 30 so that way we know on the fifth hour car park A is 280 pennies and car park B is 270 pennies so the fifth hour and anything after is cheaper at car park B and anything below five hours is cheaper at car par A.