The first thing I would do is convert that 1.2 kilograms of salt to grams; that would ensure that all the units are the same so we can perform calculations on them.
1.2kg = 1200g
Next, I would find out how many students can do the experiment with 1200g of salt, by finding it how many 25g are in 1200g (by dividing them).
That means we still have 80 students left to provide salt for (128 - 48).
Therefore, he needs an additional 80 amounts of 25g of salt.
Therefore he needs:
1.2kg = 1200g
Next, I would find out how many students can do the experiment with 1200g of salt, by finding it how many 25g are in 1200g (by dividing them).
That means we still have 80 students left to provide salt for (128 - 48).
Therefore, he needs an additional 80 amounts of 25g of salt.
Therefore he needs: