The area of the trapezium is 60 cm². The distance between two parallel sides is 10 cm. one of the parallel side lengths is 5 cm. calculate the length of the other parallel side.

Given, 

The area of the trapezium is 60 cm².

The distance (height) between two parallel sides is 10 cm.

One of the parallel sides of the trapezium is 5 cm.

Let the length of the other parallel side be 'b'.

Sum of parallel sides of the trapezium = 5 + b.

Area of the trapezium = $\frac{1}{2}$x (Sum of parallel sides) x (Height). 

$\begin{array}{rcl}60& =& \frac{1}{2}\times \left(5+\mathrm{b}\right)\times 10\end{array}$

$\begin{array}{rcl}\mathrm{b}& =& 12-5=7 \mathrm{cm}\end{array}$

Therefore, the length of the other parallel side is 7 cm.