We need to solve the expression below for "r":
[tex]5\cdot(r-10)=-51[/tex]We need to isolate the "r" variable on the left side to determine its value. To do that we will need to apply the distributive property for the product betwwen 5 and (r-10). We have:
[tex]\begin{gathered} 5r-50=-51 \\ 5r=-51+50 \\ 5r=-1 \\ r=-\frac{1}{5} \end{gathered}[/tex]