We know that all the sides of a rhombus are equal.
Let one side be a , thus perimeter = 4a =32
= a = 32/4 = 8m
Now the diagonal divides the rhombus into two triangles of sides 4m, 4m and 10m
Thus area of 1 triangle by herons formula
= 31.225 m²
Total area of Rhombus = 31.225 X 2 = 62.450²
Cost of painting = 5 X 64.450
Now it is said to paint both the side, therefore cost to paint the other side = Rs.312.50
Total Cost = 312.50 + 312.50
Hope that helps !!