Write the system of equations as an augmented matrix
⎧
⎪
⎨
⎪
⎩
y
+
6
s
−
m
=
150
6
y
+
28
s
−
3
m
=
250
2
y
+
9
s
−
m
=
200

Starting at home, emily traveled uphill to the hardware store for 606060 minutes at just 666 mph. she then traveled back home along the same path downhill at a speed of 121212 mph. what is her average speed for the entire trip from home to the hardware store and back?