Answer: Use a compass to measure the length of AB. Draw an arc from point B (or point A) with that distance. Extend line AB through that arc and label the intersection as point C. AC is twice the length of AB.
We will use the equation: r t = 3/4 r ( t+12 ) /:r t = 3/4 t + 9 t - 3/4 t = 9 1/4 t = 9 t = 9 * 4 = 36 minutes ( takes a trip to the market ) 36 + 12 = 48 minutes The ride home takes 48 minutes.