The task is to generate the correct answer for a given math problem.

Problem: find the area of trapezium whose parallel sides are 20 cm and 18 cm long , and the distance between them is 20 cm ?
380 cm 2

Problem: if a - b = 5 and a 2 + b 2 = 31 , find the value of ab .
3

Problem: 10 x 0.5 = ?