MASS*GRAV*HEIGHT=PE
MASS=3
GRAV=9.8
HEIGHT=4.5
3*9.8*4.5=132.3
POTENTIAL ENERGY= 132.3
Answer:
80 members
Step-by-step explanation:
Let the band members be= b and the chorale members= c
Then, according to question, b=c+30 and 
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Now, substituting the value of b=c+30, we get
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Therefore, 

Therefore, there are 80 members in the band.