X - 5y = -20
y = ax + b

I Graphed It

Step-by-step explanation:

100= 10+ 16t

Step-by-step explanation:

If beginning at 10 percent you initially are only in need for 90% charge. Earning 16% every thirty minutes you can initially do x4 for two hours on the charger and know you aren't at 100 yet. (16x4)+10= 64+10= 74. 100-74= 26. You need one more hour (total of 6 half hours) on the charger.

Another way of doing it could be 16÷90 and getting 5.blahblahblah and rounding up.