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o-na [289]
3 years ago
5

Please help! provide thorough explanation and use elimination method!!

Mathematics
1 answer:
ICE Princess25 [194]3 years ago
8 0

Multiply both sides of the second equation by 100 to get rid of the decimals:

0.05<em>n</em> + 0.10<em>d</em> = 1.50

==>  5<em>n</em> + 10<em>d</em> = 150

Multiply both sides of the first equation by -5:

<em>n</em> + <em>d</em> = 21

==>  -5<em>n</em> - 5<em>d</em> = -105

Add the two equations together:

(5<em>n</em> + 10<em>d</em>) + (-5<em>n</em> - 5<em>d</em>) = 150 + (-105)

Notice that the terms containing <em>n</em> get eliminated and we can solve for <em>d</em> :

(5<em>n</em> - 5<em>n</em>) + (10<em>d</em> - 5<em>d</em>) = 150 - 105

5<em>d</em> = 45

<em>d</em> = 45/5 = 9

Plug this into either original equation to solve for <em>n</em>. Doing this with the first equation is easiest:

<em>n</em> + 9 = 21

<em>n</em> = 21 - 9 = 12

So Donna used 12 nickels and 9 dimes.

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