a circular path of 13 m radius has marginal walk 2 m wide all round it . find the cost of leveling the walk at 25 p per m 2 ?
"π ( 152 - 132 ) = 176 176 * 1 / 4 = rs . 44 answer : c"
multiply(25, subtract(circle_area(add(13, 2)), circle_area(13)))