Math

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CTHook CTHook
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Math

McGenius McGenius
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Re: Math

x = miles riding
y = miles walking

x + y = 72   total trip was 72 miles
x/15 + y/4 = 7   took 7 hours

x + y = 72    top equation stays same
4x + 15y = 420   multiplied bottom equation by 60 to clear fractions

-4x - 4y = -288   multiplied top equation by -4
4x + 15y = 420   bottom equation stays same
-----------------
11y = 132   added the equations
y = 12   divided by 11

x + y = 72
x + 12 = 72   substituted 12 for y
x = 60   subtracted 12

60 miles riding
12 miles walking


*McGenius*