Testing an expression:
Speed x time = distance
s*t=d
12(t)=60-10
12(t)=50
t=50/12 or t ≈ 4.16 hours
But we want minutes and there are 60min in one hour, so:
t=(50/12)*60
t=250 minutes.
——
12mi/h can be rewritten as 12mi/60min. That can simplify to 1mi/5minutes. So she is traveling at 1 mile per 5 minutes. Since she already rode 10 miles, that would have taken her 50 minutes.
60 is divisible by 12, and 60/12 = 5. So if she travels 12mi/h, it will take her 5 hours to travel 60 miles. Im minutes this is shown by 5 x 60 = 300, so it would take 300 minutes.
It seems that by “how many MORE minutes must she ride..” the 10 miles she already traveled is counted toward the 60 miles. Those 10 miles took 50 minutes. So she really only has 50 miles left to go.
300 minutes - 50 minutes = 250 minutes. She must ride 250 more minutes to reach 60 miles total.