The base of a triangle is five-sixth of the base of a parallelogram having the same area as
that of the triangle, The ratio of the corresponding heights of the triangle to the parallelogram will be:

Area of parallelogram = b $$\times$$ h

Area of triangle = $$\frac{1}{2}bh$$

where b is the length of base and h is the height.

A/c to question , base of triangle = $$\frac{5}{6}th of base of parallelogram$$

They have equal area , so ,

$$\frac{1}{2} \times b_{1}h_{1} = b_{2}h_{2}$$

$$\frac{1}{2} \times \frac{5}{6}b_{2} h_{1} = b_{2}h_{2}$$

$$\frac{b_{1}}{b_{2}} = \frac{12}{5}$$

So, the answer would be option a)12:5.