Loisa will pay a total of $40 x 4 = $<<40*4=160>>160 for the first 4 months.
She will pay a total of $35 x 4 = $<<35*4=140>>140 for the next four months.
And she will pay a total of $30 x 4 = $<<30*4=120>>120 for the last four months.
Thus, she will pay a total of $100 + $160 + $140 + $120 = $<<100+160+140+120=520>>520 for 12 months including the down payment.
Therefore, Loisa can save $520 - $450 = $<<520-450=70>>70 if she buys the tablet in cash.
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