Rajesh walked 10 kilometers less than 4 times the distance that Hiro walked. Together they walked 25 kilometers. How many kilometers did Rajesh walk?
Let H = distance Hiro walked
4H - 10 = distance Rajesh walked.
H + 4H - 10 = 25
5H - 10 = 25
5H = 35.
Hiro walked 7 km so Rajesh walked 4(7) - 10 = 
<gadget id="calculator">7*4-10</gadget>
<output>18</output>
18 km.
Rajesh walked 
<gadget id="calculator">18</gadget>
<output>18</output>
18 kilometers.

<result>18</result>