Question: 5m(2m-1)-3m
1. **State the problem:** Simplify $5m(2m-1)-3m$.
2. **Use the distributive property:**
$$5m(2m-1)=5m\cdot 2m+5m\cdot(-1)$$
$$=10m^2-5m$$
3. **Substitute back into the expression:**
$$10m^2-5m-3m$$
4. **Combine like terms:**
$$-5m-3m=-8m$$
So the expression becomes
$$10m^2-8m$$
5. **Final answer:**
$$10m^2-8m$$