Answer:
Step-by-step explanation:
10+60t≤280
60t≤280-10
60t≤270
6t≤27
2t≤9
t≤9/2
t≤4.5
t=4 hours
first subtract $10 from$280 and you get $270
270 divided by 60 = 4.5
so the answer is four and a half hours
