Question

suppose j varies jointly with g and v, and j=1 when g=4 and v=5. what is j when g=10 and v=9?

Answer 1

j$\alpha gv$
j=agv where a is a constant of proportionality.
j=1 when g=4 and v=5
1=a*4*5
1=20a
a=1/20
a= 0.05
j=0.05gv
When g=10 and v=9,
j=0.05*10*9
j=0.5*9
j=4.5