Question 1199900
<pre>
Buduli covers a distance of 8km to his house in 1hour.He walks part of the distance at 6km/h and runs the rest at 10km/h. How many kilometers did he run.

Let distance he ran be D
Then distance walked = 8 - D
Time taken to run and walk the 2 distances: {{{matrix(1,4, D/10, and, (8 - D)/6, respectively)}}}

We then get the following TIME equation: {{{matrix(1,3, D/10 + (8 - D)/6, "=", 1)}}}
                                      3D + 5(8 - D) = 30 ---- Multiplying by LCD, 30
                                       3D + 40 - 5D = 30
                                            3D - 5D = 30 - 40
                                               - 2D = - 10
                             Distance he ran, or {{{highlight_green(matrix(1,6, D, "=", (- 10)/(- 2), "=", 5, km))}}}</pre>