squash = cordial + water
400 ml = 50 ml + x ml
350 ml = x ml
Therefore, 350 ml are water.
350 ml / 400 ml = 0.875 = 
So the answer is 7 / 8
The boat travels 501 miles in 3 weeks.
Given a slope
, the slope
of a line perpendicular to
is the opposite of the inverse of 
In other words:

So, the slope of CD is -5/2.
11. Assuming distance is proportional to time,
.. (3 h)/(7 h) = d/(665 km)
.. d = (665 km)*(3/7) = 285 km . . . . . . selection B
12. (30 L)/(1.5 L/min) = 20 min . . . . . . selection C