how do i solve
r=124sqrt8000/10

Question

anonymous · Answer

technically it is already solved. all you can do from here is simplify. is that what you want done?

my4babiesandme · Answer

During the first part of a trip, a canoeist travels 80 miles at a certain speed. The canoeist travels 19 miles on the second part of the trip at a speed 5 mph slower. The total time for the trip is 5 hrs. What was the speed on each part of the trip? round to nearest hundredth. this is the problem i am doing and that is the step in i can understand the example to

dumbcow · Answer

Equations
$$80 = r*t_{1}$$
$$19 = (r-5)t_{2}$$
$$t_{1} +t_{2} = 5$$
$$\rightarrow \frac{80}{r} + \frac{19}{r-5} = 5$$
$$80(r-5) + 19r = 5r(r-5)$$
$$5r^{2} -124r+400 = 0$$
$$r = \frac{124 \pm \sqrt{7376}}{10}$$

dumbcow · Answer

From here just use a calculator, ignore answer where r < 5
$$r = 20.99$$

my4babiesandme · Answer

ok what i do not understand is how to go from the last step what do i do to get the 20.99?

dumbcow · Answer

use a calculator
$$\sqrt{7376} = 85.8836$$
$$124 + 85.8836 = 209.8836$$
$$\frac{209.8836}{10} = 20.99$$

my4babiesandme · Answer

thank you so much you are awesome

dumbcow · Answer

no problem

my4babiesandme · Answer

i so understand it now i have done 3 problems to make sure thank you so much