Question

The sum of 13 and twice a number h

Answer 1

If I'm reading the question right, you're asking for
`13+2n`, right? Well, if we assume this equation equals zero, then we can subtract 13 from each side to get
`2n=-13`. Divide 2 from each side and for your final answer, drumroll please, ........
`n=-13/2`. Hope that helps.

Answer 2

So,

"The sum of 13"
13 +

"and twice a number h"
2(h) or 2h

13 + 2h