Question

The Sum of twice a number and 5 is at most 15. What are the possible values for the number?

Answer 1

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.

$2x+5\le 15$

Let's solve.

$2x+5\le 15\\ \\ 2x\le 15-5\\ \\ 2x\le 10\\ \\ x\le \frac { 10 }{ 2 } \\ \\ x\le 5$

$x\quad \in \quad \left[ -\infty ,5 \right]$

If the number is a natural number. The values it can take is, $x\quad \in \quad \left[ 0,1,2,3,4,5 \right]$

Answer 2

5 10=15
3x5=15
so 3.5.10