Answer:
28r + 8r + r = 55
Step-by-step explanation:
Some values you know (given or calculated) and some things you do not know.
RATE TIME DISTANCE
BIKE 2*8r 1.75
RUN 8r
SWIM r 1
Total 55
Give a variable to unknown running speed and fill in everything.
RATE TIME DISTANCE
BIKE 16r 1.75 28r
RUN 8r t 8rt
SWIM r 1 r
Total 55
Notice some trouble? WHY? I missed seeing the "ran for one hour". the variable t is KNOWN! This will be corrected here:
RATE TIME DISTANCE
BIKE 16r 1.75 28r
RUN 8r 1 8r
SWIM r 1 r
Total 55
Calculations used to fill out the graph:
Then her running speed was 8r,
and her biking speed was 2*(8r) = 16r.
Swimming for 1 hour, Jenny covered the distance of 1*r = r kilometers.
Biking for 1.75 hour, Jenny covered the distance of 1.75*16r = 28r kilometers.
Running for 1 hour, Jenny covered the distance of 1*2r = 8r kilometers.
Everything is filled and looks good. There is a sum of distances in just the one single variable, r.
Solve for r, and this is the swimming speed.
28r + 8r + r = 55
