y =∑i=36 2i+1

The given expression is a summation notation, also known as sigma notation. It represents a series of terms added together. The expression "y = ∑i=3 to 6 (2i+1)" means that we are summing the terms of the sequence (2i+1) for i values from 3 to 6.

Here are the steps to solve it:

1. Substitute i = 3 into the expression 2i + 1: 2*3 + 1 = 6 + 1 = 7

2. Substitute i = 4 into the expression 2i + 1: 2*4 + 1 = 8 + 1 = 9

3. Substitute i = 5 into the expression 2i + 1: 2*5 + 1 = 10 + 1 = 11

4. Substitute i = 6 into the expression 2i + 1: 2*6 + 1 = 12 + 1 = 13

5. Add all the results together to get the final answer: y = 7 + 9 + 11 + 13 = 40

So, y = 40.