Anna has $504 left after buying computer.
Step-by-step explanation:
Given,
Amount saved by Anna each month = $30
Time period = 
1 year = 12 months

Amount saved in 42 months = 42*30 = $1260
She spent 60% of her savings.
Amount spent = 60% of 1260
Amount spent = 
Amount spent = $756
Amount left = Savings - Amount spent
Amount left = 1260 - 756 = $504
Anna has $504 left after buying computer.
Keywords: subtraction, division
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