I need help to get the answer,

Answer:
4.25 hours
Step-by-step explanation:
A fully charged phone would be at 100%, so we'll set y equal to 100 and solve for x:
100=20x+15
85=20x
4.25=x
So Sammi's phone will be fully charged in 4.25 hours.
Answer:
4.25 hours
Step-by-step explanation:
"Fully charged" means the percentage should be 100%.
Substitute 100 for y then solve for x.
[tex]100=20x+15\\85=20x\\x=\frac{85}{20}\\x=4.25 \text{ hours}[/tex]