How would you solve the following using a table? Andrew cashes a $180 check and wants the money in $10 and $20 bills. The bank teller gives him 12 bills. How many of each kind of bill does he receive?

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Answer 1 · 2014-11-26T06:16:54

We can solve this problem using a table and a pair of linear equations.

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(The dollar sign has been disregarded.)

Now, we know that he has received a total amount of $180. Thus, our first equation is:

$10x+20y=180$ --------(1)

Now, we need another equation. We know that he has received 12 bills in total. Therefore, our second equation is:

$x+y=12$

To make at least one variable term exactly like in the first equation, I will multiply this equation by 10, getting:

$10x+10y=120$ --------(2)

Subtracting equation (2) from (1),

$(+)10x+20y=180$
$(-) 10x+10y=120$
$---------$
$(=) 0 +10y=60$

Therefore, $y=60/10$

$y=6$

Substituting $y=6$ in (2),

$10x+10(6)=120$
$10x+60=120$
$10x=120-60$
$10x=60$

$x=60/10$

$x=6$

Thus, we can conclude that he receives 6 bills each of $10 and $20.