Melissa has a rope that is 84 feet long. she is cutting it into 7-foot pieces to make a ropes. How many jump ropes can she make?

So,

Melissa's rope is 84ft. long.

Each piece must be 7ft. long.

We divide the length of the rope by the required length of each piece.

Now we have a fraction: 84/7

Prime Factorization

Prime factored form of 84: 2*2*3*7

Prime factored form of 7: 7

Cross out 7's

2*2*3/1 or 12/1 or 12

Melissa can make 12 ropes.