How do I answer question #4?

The answer to your question is below

Step-by-step explanation:

4.-

4a.                     72

                       _x 9

                         638

4b. The error this student is doing is that he multiplies the first number but he must add the decenes of this result to the result of the multiplication of the second number and he is not doing that.

4c.- I told him the correct way to solve multiplications.

   a) Multiply the first number and only write the units.

   b) If the are decenes add then to the units of the result of the multiplication of the second number.

Example                                

                                72            9 x 2 = 18

                               x9             Just write the 8

                                  8

                                72

                               x 9

                               648           9 x 7 = 63 + 1 from the previous operation

                                                          = 64

4/6 = 2/3

so it should take 3/3 hours per man. so 9 hours is the answer 3*3 =9

step-by-step explanation: