2 times the sum of 1 and some number is 30. What is the number?

2 times the sum of 1 and some number is 30. What is the number?

We let the phrase "some number" equal the variable x.

The sum of 1 and some number is:
x + 1

2 times the sum:
2(x + 1)

The word "is" means equal to, so we set 2(x + 1) = 30