Question

Alfonso traveled 100 miles in 4 hours. Then he increased his speed by 5 miles per hour. How long did it take him to travel the last 120 miles at the new speed?

Answer 1

4 hours

Explanation

Step 1

find the inital speed

$\text{speed}=\frac{dis\tan ace}{\text{time}}$

let

distance= 100 miles

time= 4 hours

replace,

$\begin{gathered} \text{speed}=\frac{dis\tan ace}{\text{time}} \\ \text{speed}=\frac{100\text{ miles}}{4\text{ hours}} \\ \text{speed}_1=25\text{ miles per hour} \end{gathered}$

Step 2

Then he increased his speed by 5 miles per hour.

$\begin{gathered} \text{speed}_2=speed_1+5 \\ \text{speed}_2=25\text{ miles per hour + 5 miles per hour} \\ \text{speed}_2=30\text{ miles per hour} \end{gathered}$

Step 3

finally, let

distance2=120 miles

time 2= unknown

speed2= 30 miles per hour

replace

$\begin{gathered} \text{speed}=\frac{dis\tan ace}{\text{time}} \\ 30\text{ }\frac{mi}{h}=\frac{120\text{ miles}}{t_2} \\ 30=\frac{120}{t_2} \\ t_2=\frac{120}{30} \\ t_2=4\text{ hours } \end{gathered}$

so, it will take 4 hours

I hope this helps you