Subtract :
`ab-bc-ca` from `3ab +2bc-4ca`

Answer

To solve the problem of subtracting \( ab - bc + ca \) from \( 3ab + 2bc - 4ca \), we can follow these steps:

### Step 1: Write the expression for subtraction
We need to subtract \( ab - bc + ca \) from \( 3ab + 2bc - 4ca \). This can be written as:
\[ (3ab + 2bc - 4ca) - (ab - bc + ca) \]

### Step 2: Distribute the negative sign
Next, we distribute the negative sign across the second expression:
\[ 3ab + 2bc - 4ca - ab + bc - ca \]

### Step 3: Combine like terms
Now, we will combine the like terms:
- For \( ab \): \( 3ab - ab = 2ab \)
- For \( bc \): \( 2bc + bc = 3bc \)
- For \( ca \): \( -4ca - ca = -5ca \)

Putting it all together, we have:
\[ 2ab + 3bc - 5ca \]

### Final Answer
Thus, the result of subtracting \( ab - bc + ca \) from \( 3ab + 2bc - 4ca \) is:
\[ \boxed{2ab + 3bc - 5ca} \]

---