Answer :
Let's call that number x, twice the number will be 2x, sum of it and 5 is, 2x+5. So if this expression is at most 15, it means, it can be only less than 15 and equal to 15. Let's show this as an inequality.
[tex]2x+5\le 15[/tex]
Let's solve.
[tex]2x+5\le 15\\ \\ 2x\le 15-5\\ \\ 2x\le 10\\ \\ x\le \frac { 10 }{ 2 } \\ \\ x\le 5[/tex]
[tex]x\quad \in \quad \left[ -\infty ,5 \right] [/tex]
If the number is a natural number. The values it can take is, [tex]x\quad \in \quad \left[ 0,1,2,3,4,5 \right] [/tex]
[tex]2x+5\le 15[/tex]
Let's solve.
[tex]2x+5\le 15\\ \\ 2x\le 15-5\\ \\ 2x\le 10\\ \\ x\le \frac { 10 }{ 2 } \\ \\ x\le 5[/tex]
[tex]x\quad \in \quad \left[ -\infty ,5 \right] [/tex]
If the number is a natural number. The values it can take is, [tex]x\quad \in \quad \left[ 0,1,2,3,4,5 \right] [/tex]
