Answer: 1.5 hours
Step-by-step explanation:
If Thiago and Brandon move in opposite directions at speeds of 80mph and 70mph then after 1 hour Thiago will have traveled 80 miles and Brandon will have traveled 70 miles.
Since they are in opposite directions then the distance is from
[tex]70 + 80 = 150\ miles[/tex]
Then we know that after t hours have elapsed they are 225 miles
Then we pose the following equation
[tex]80t + 70t = 225[/tex]
Now we solve for t
[tex](80 + 70) t = 225[/tex]
[tex]150t = 225\\\\t=\frac{225}{150}\\\\t=1.5\ hours[/tex]