jony walks along sunrise boulevard daily . he starts walking at 07 : 00 from block 10 and walks to block 90 where he turns around and walks back to block 70 , where he stops at 07 : 40 . the blocks along the boulevard are numbered sequentially ( 1 , 2,3 ) , and each block measures 40 meters . what is jony ' s speed in meters per minute ?
total distance from 10 to 90 = 80 + from 90 to 70 = 20 so the dist is 100 × 40 ( per block dist ) speed = 4000 mts / 40 min = 100 m / min b is the answer
divide(add(multiply(subtract(90, 10), 40), multiply(subtract(90, 70), 40)), 40)