To determine how much force Joaquin saves by using the lever, we first need to calculate the amount of force he uses with the lever.
The mechanical advantage of the lever is 3, which means that the lever allows him to lift the crate with a force that is one-third of the force he would normally need to apply.
To find the force required using the lever, we can use the following formula:
\[ \text{Force with lever} = \frac{\text{Force needed without lever}}{\text{Mechanical Advantage}} \]
Substituting in the values:
\[ \text{Force with lever} = \frac{312 , \text{N}}{3} = 104 , \text{N} \]
Now, to find out how much force he saves by using the lever, we subtract the force used with the lever from the force needed without the lever:
\[ \text{Force saved} = \text{Force needed without lever} - \text{Force with lever} \]
\[ \text{Force saved} = 312 , \text{N} - 104 , \text{N} = 208 , \text{N} \]
Therefore, the amount of force Joaquin saves by using the lever is 208 N.