Question

I need help to get the answer,

Answer 1

4.25 hours

Explanation:

"Fully charged" means the percentage should be 100%.

Substitute 100 for y then solve for x.

`100=20x+15\\85=20x\\x=(85)/(20)\\x=4.25 \text{ hours}`

Answer 2

4.25 hours

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.