Question

Donald sells 760 marbles every day. He sells each marble for 1.5 dollars.

Answer 1

Well, let's see. First we would need to find how much money he earns each DAY. To find THAT, we would need to multiply 760 times 1.5, which would be $1,140. Now, in order to find out how many DAYS it will take to make $3,420, you would divide 3,420 divided by 1,140, which will be 3. So it will take 3 days to earn $3,420.
I hope I helped! =D

Answer 2

3420/1.5 is 2280. This means Donald would have to sell 2280. 2280/760 is 3 meaning he would have to sell marbles for 3 days :)