How can i do this one ☝️

Hey there!
Let's start by adding 5 to both sides. This eliminates the -5.
1 = r/20
Now to solve for r we can multiply both sides by 20.
20 = r
Check
-4 = 20/20 - 5
-4 = 1 - 5
-4 = -4
Your answer is r = 20.
Hope this helps!
Answer:
Step-by-step explanation:
-4 = [tex]\frac{r}{20}[/tex] - 5
⇒ -4 + 5 = [tex]\frac{r}{20}[/tex]
⇒ 1 = [tex]\frac{r}{20}[/tex]
⇒ 1 × 20 = r
⇒ 20 = r