Answer: r=12.3 *The answer must have a positive sign or decimal point.*
Explanation:
First, you had to do is add 17.1 from both sides of an equation.
[tex]r-17.1+17.1=-4.8+17.1[/tex]
And then, simplify by equation.
[tex]17.1+-4.8=12.3[/tex]
You can also add by the numbers.
[tex]12.3+4.8=17.1[/tex]
[tex]r=12.3[/tex]
Hope this helps!