The ratio of the bases of two triangles is a : b. If the ratio of their corresponding altitudes is c : d, find the ratio of their areas (in the same order).

The correct answer is: ac : bd

It is given that ratio of bases of two triangle is a : b
⇒ Bases of the triangles = ax , bx
Similarly, it is given that ratio of altitudes is c : d
⇒ Altitudes of the triangle = cy , dy
Area of first triangle = 
= 
Area of second triangle = 
Ratio of the areas of two triangle
= 
= 
Hence, ratio of area of two triangles is ac : bd