The load is the weight of the rock that Jonathan lifts:
[tex]L=3000 N[/tex]
The effort instead is the force applied in input to the lever in order to lift the rock:
[tex]E=300 N[/tex]
So, the ratio between load and effort for this exercise is
[tex] \frac{L}{E}= \frac{3000 N}{300 N}=10 [/tex]
So, the ratio is 10:1.