Question

In a walkathon to raise money for a charity, Elisa walked a certain distance at 5mi/h and then jogged twice the distance at 8mi/h. Her total time walking and jogging was 2hr and 15min. How many miles long was the walkathon?

Answer 1

Also, it's math.

Answer 2

Also, it's math.

Answer 3

I would write 2 equations, 1 for
jogging and 1 for walking
$d%5Bj%5D+=+r%5Bj%5D%2At%5Bj%5D$
$d%5Bw%5D+=+r%5Bw%5D%2At%5Bw%5D$
----------------------
given:
$r%5Bj%5D+=+8$ mi/hr
$r%5Bw%5D+=+5$ mi/hr
$d%5Bj%5D+=+2d%5Bw%5D$
$t%5Bj%5D+%2B+t%5Bw%5D+=+2.25$ hrs
------------------------
Now rewrite the equations
$d%5Bj%5D+=+r%5Bj%5D%2At%5Bj%5D$
$2d%5Bw%5D+=+8%2A%282.25+-+t%5Bw%5D%29$
$2d%5Bw%5D+=+18+-+8t%5Bw%5D$
$d%5Bw%5D+%2B+4t%5Bw%5D+=+9$
and
$d%5Bw%5D+=+r%5Bw%5D%2At%5Bw%5D$
$d%5Bw%5D+=+5t%5Bw%5D$
Substituting:
$5t%5Bw%5D+%2B+4t%5Bw%5D+=+9$
$9t%5Bw%5D+=+9$
$t%5Bw%5D+=+1$ hr
And, since
$d%5Bw%5D+=+5t%5Bw%5D$
$d%5Bw%5D+=+5$ mi
And, since
$d%5Bj%5D+=+2d%5Bw%5D$
$d%5Bj%5D+=+2%2A5$
$d%5Bj%5D+=+10$ mi
The walkathon was $5+%2B+10+=+15$ mi
check:
$d%5Bj%5D+=+r%5Bj%5D%2At%5Bj%5D$
$10+=+8%2At%5Bj%5D$
$t%5Bj%5D+=+1.25$ hr
and
$d%5Bw%5D+=+r%5Bw%5D%2At%5Bw%5D$
$5+=+5%2At%5Bw%5D$
$t%5Bw%5D+=+1$ hr
$t%5Bj%5D+%2B+t%5Bw%5D+=+2.25$