Arianna is taking care of her uncle's dog during the week. he left 3 cans of food for 5 days. how much good should she give each day assuming the dog eats exactly the same amount each day

it's undefined because anything multiplied by 0 is 0. that said, 7 days is 168 hours

multiplication is multiplication.   it might feel harder depending on what level of math you are in, but generally it will be the same old stuff, while implementing some new concepts and methods of solving work.