Question

Hey can anyone help me with this problem

Answer 1

Answer:

The speed of River's mom drove for 10 miles distance is 0.234 mph.

The speed of  River's mom drove for 25 miles is 10.234 mph.

Step-by-step explanation:

Given as :

The first distance cover by River's mom = 10 miles

The rate of speed = x mph

The second distance cover by river's mom = 25 miles

The rate of speed = x + 10 mph

The total driving time = 45 min

Now, According to question

$Time = \frac{Distance}{Speed}$

So, $45 = \frac{10}{x}+\frac{25}{x+10}$

Now dividing by 5 on both side we get;

$9=\frac{2}{x}+\frac{5}{x+10}\\\\9= \frac{2(x+10)+5x}{x(x+10)}\\\\9= \frac{2x+20+5x}{x^2+10x}\\\\9(x^2+10x)= 7x+20\\9x^2+90x-7x-20=0\\9x^2+83x-20=0$

Solving this quadratic equation we get;

$x=\frac{-b\±\sqrt{4ac}}{2a}$

$x=\frac{-83\±\sqrt{4\times9 \times 20}}{2\times 9}\\\\x= \frac{-83\±\sqrt{720}}{18}\\ \\x= \frac{-83+87.22}{18} \ \ \ or \ \ x = \frac{-83-87.22}{18}\\\\x= 0.234 \ \ \ or\ \ \ \ x= - 9.4567$

Since speed cannot be in negative hence we will consider x= 0.234

So, The speed for 10 miles distance = x = 0.234 mph

and The speed of 25 miles = x + 10 = 0.234 + 10 = 10.234 mph

Hence The speed of River's mom drove for 10 miles distance is 0.234 mph

and The speed of  River's mom drove for 25 miles is 10.234 mph