PROBLEM SOLVING: 1. In a movie house, there 20 Seats in the first row and there are 25 rows in all. Each successive row contains 1 additional seat. how many seats are there in theatre?
2. a grocer wishes to pile cans of milk so that the top layer will contain 4 cans and each layer will have one more than the layer above. If there are 12 layers in all, how many cans will the grocer need?
3. Susan promised to increase her daughter's monthly allowance. She gave her 400 pesos on the first month, 500 pesos on the second month and 600 pesos on the third month and so on. How much will her daughter receive on the 8th month?
4. Every year, a certain fruit tree produces 5 more fruits than the previous year. If it bore 20 fruits in 1998, how many would it bear in 2005?