If A represents the number of apples purchased at 15 centa each, total value of apples bought will be 15A...................(1)
If B represents the number of banana purchased at 10 cents each, total value of bananas bought will be 10B................(2)
So ,the total value of purchase of apples and bananas is the addition of two equations (1)+(2)
i.e. 15A+10B
eg. if number of apples and banana purchased is 5 each then the total value of the purchase will be= 15*5+10*5= 125.