Jenny can jog twice as fast as she can walk. She was able to jog the first 12 miles to her grandmother house but then she tried and walked the remaining 3 miles. If the total trip took 2 hours then what was her 평균 jogging speed

해법

J e nn y c an j o g tw i ce a s f a s t a s s h e c an w a l k . S h e w a s ab l e t o j o g t h e f i rs t 12 mi l es t o h er g r an d m o t h er h o u se b u t t h e n s h e t r i e d an d w a l k e d t h e re mainin g 3 mi l es . I f t h e t o t a l t r i p t oo k 2 h o u rs t h e n w ha t w a s h er a v er a g e j o gg in g s p ee d

joging speed : 9

솔루션 단계

Translate the problem into an equation:

\frac{12}{x} + \frac{3 \cdot 2}{x} = 2

x

해결 대상

, \frac{12}{x} + \frac{3 \cdot 2}{x} = 2 : x = 9

joging speed : 9