Question

a gardener is making a triangle planting with 35 plants in row ,31 in the second row ,27 in the third row and so on . if the pattern is considered how many plants will be there in the last row?

Answer 1

The nth row has 35-4(n-1) = 39-4n plants.
So, what is the largest multiple of 4 less than 39? Subtract that from 39.

Or, just divide 39 by 4. The remainder is how many plants are in the last row. It is the row that is too short to subtract 4 from it again.

Answer 2

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