Answer:
3/4
Step-by-step explanation:
3/5(1+p)-21/20
3/5+3/5p=21/20
3/5p=21/20-3/5
3/5p=21/20-12/20
3/5p=9/20
p=9/20÷3/5
p=9/20*5/3
p=45/60
p=3/4