Thirty divided by the sum of three and a number, equals five.

Answer 1

The complicated part is "the sum of three and a number." So let's put that aside for now.

That leaves us with "Thirty divided by [___] equals five," and it's pretty easy to figure out that the blank there is six.

Wait, so "the sum of three and a number" is six? The sum of three and three is six.

The lesson here is to isolate the hard parts, and keep things simple.

Answer 2

Answer 3

30 / (3 + n) = 5

30 =5(3 + n)

6 = 3 + n

3 = n