15 mph then slowed to mph

Question

if justin road his bike at a rate of 15mph and then slowed to 10mph. he road 30 min longer at 15mph than he did at 10mph. If he traveled a total of 25mi, how long did he ride at the faster rate

Answer 1

t represents the time at 10mph

15(t + 0.5) + 10t = 25               30min = 0.5hr

15t + 7.5 + 10t = 25

 

Can you solve for "t?"