let Tina bought X number of nail polish any Y number of lip gloss.
then, X+Y=9
or,X=9-Y
Also,4.5 X+7 Y=50.5
or, 4.5 (9-Y) +7 Y=50.5
or, Y =4.........................................(i)
so, X= 9-4
= 5........................................(ii)
hence, she bought 5 nail polish and 4 lip gloss