All you have to do is first make the 3/5 into a decimal so it can be multiplied by the 40. 3/5 is .60 so you can use that number. (.60*40) and that should be w=equal to 24 which is your answer.
5 goes into 40, 8 times so cross out the 5 and replace it with 1 and cross out the 40 and replace it with 8. Then you are left with 3 x 8 which equals 24.
