1) y varies directly as x and y =4 when x=-5.
2) y varies inversely as x and y=6 when x=8.
3) z varies jointly as x and y if z=4 when x=2 and y=20
4). r varies directly as s and inversely as the square of u and r=2 when s=16 and u=2
5) w varies inversely as z and w=3 when z=18.
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