Question 32403
<pre><B> X=WALKING SPEED
X+10=RIDING SPEED
Eqaution:
*[tex \frac{12}{x+10}+\frac{8}{x}=5]
Cross multiply:
12(x)+8(x+10)=5[(x)(x+10)]
{{{20x+80=5(x^2+10x)}}}
{{{5x^2+30x-80=0}}}
{{{x^2+6x-16=0}}}
{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} 
a=1, b=6, c=-16
{{{x = (-6 +- sqrt( 6^2-4*1*-16 ))/(2*1) }}} 
Simplfy:
x=-8 or x=2
remove negative x=2
2+10=12
<font color = green>Hence, his walking speed was 2mph and his bike speed was 12 mph.</font>
Paul.