Year 12s: what will be the first way you research your future options? >>

quadratic and simultaneous eqn

Atif walks for x hours at 5 km/h and runs for y hours at 10km/h. He travels a total of 35km average speed is 7km/hr. Find the value of x and y

Reply 1

FlyingNinja1

Turn x hours and 5km/h into distance. Do the same with Y. Do xterms + yterms = 35km
You can probably figure out the rest

thx a lot

distance travelled: 35km
total time: x+y hours
average speed: distance/time
7=35/(x+y)
x+y=35/7 ... eq. 1

total distance= xh(5km/h) + yh(10km/h)
35=5x+10y
7=x+2y ... eq.2

eq.2, x=7-2y

Substitute x=7-2y to eq.1
7-2y+y=35/7
7-y=35/7
49-7y=35
-7y=-14
y=2

x=7-2(2)
x=7-4
x=3

I'm not really sure if this is correct though.