There are two sizes of trucks available: larger truck with a 2.5-ton payload, and smaller trucks with 1.5-ton payload. to unload a freight train 21 larger trucks are needed . how many smaller trucks would be needed for the same job?

You can find the answer to this question by multiplying 21 by 2.5 to find the total weight ton which would be 52.5, then you would divide 52.5 by 1.5 to find the number of small trucks needed to equal 52.5 ton which would be 35 smaller trucks. So your answer should be 35 smaller trucks are needed to do the same job.