Bunuel wrote:
On his trip from Alba to Benton, Julio drove the first x miles at an average rate of 50 miles per hour and the remaining distance at an average rate of 60 miles per hour. How long did it take Julio to drive the first X miles?
(1) On this trip, Julio drove for a total of 10 hours and a total of 530 miles --> \(total \ time=10=\frac{x}{50}+\frac{530-x}{60}\) --> we have the linear equation with one unknown, so we can solve for \(x\). Sufficient.
(2) On this trip, it took Julio 4 more hours to drive the first x miles than to drive the remaining distance --> \(\frac{x}{50}=\frac{y}{60}+4\), where \(y\) is the remaining distance --> we have the linear equation with two unknowns, so we can not solve for \(x\). Not sufficient.
Answer: A.
i've got sufficient with (1)
However with (2), we are told that : "it took Julio 4 more hours to drive the first x miles than to drive the remaining distance " can we have the fomular as folow:
r1 = 50m/h
r2 = 60m/h
1 hour: we have the difference miles between the first x mile and the remaining = 10m
=> with 4 hours: we can find the distance of the remaining distance = x + (10m/h x 4h) = x + 40miles
=> we have the equation with one unknown as we have solved the remaining distance.
Please tell me where i did get the wrong refers?