Question 1105045
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The other tutor's answer is not right; perhaps you can see where she made her mistake....<br>
{{{7a+3b = 19}}}  you get $1 change from a $20 bill when buying 7 burgers and 3 sodas
{{{8a+2b = 19.5}}}  you get $0.50 change from a $20 bill when buying 8 burgers and 2 sodas<br>
Use elimination: multiply the first equation by 2 and the second by 3 and subtract to eliminate y:
{{{14a+6b = 38}}}
{{{24a+6b = 58.5}}}
{{{10a = 20.5}}}
{{{a = 2.05}}}  each burger costs $2.05<br>
Substitute in either original equation to solve for y:
{{{7(2.05)+3b = 19}}}
{{{14.35=3b = 19}}}
{{{3b = 4.65}}}
{{{b = 1.55}}}  each soda costs $1.55<br>
One burger and one soda costs $3.60; you get $1.40 change from a $5 bill.