Distribute the multiplication in the last term: 5(x + 6) becomes 5x + 30. Then, 2x + 3 + 5(x+ 6) becomes 2x + 3 + 5x + 30. 2x and 5x are 'like terms' and add up to 7x; 3 and 30 are also like terms of a different type (constants) and add up to 33.
Thus we have the equivalent, simpler expression 7x + 33.
