contestada

kristen can run 9km/h and walk 3km/h. she completed a 42km marathon in 6 hours. what distance did kristen run during the marathon?

Respuesta :

carlosego
Let
 x = distance traveled running.
 y = distance traveled walking.
 x + y = 42
 1 / 9x + 1 / 3y = 6
 Solving the system of equations:
 -3 * (1 / 9x + 1 / 3y) = - 3 * (6)
 -1 / 3x + -y = -18
 Then,
 x + y = 42
 -1 / 3x + -y = -18
 Adding up:
 -1 / 3x + x = 24
 2 / 3x = 24
 x = (3/2) * 24
 x = 36 Km
 Answer:
 kristen ran 36 Km during the marathon

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