x-cost\ of\ DVD\\y-cost\ of\ video\ game\\\\ \left \{ {{3x+14y=203\ \ \ } \atop {11x+11y=220\ \ } \right. \\\\ From\ first\ second:\\11x=220-11y\ \ \ \ |:11\\x=20-y\\\\Substitute\ to\ first:\\3(20-y)+14y=203\\60-3y+14y=203\\-3y+14y=203-60\\11y=143\ \ \ \ |:11\\y=13\\\\x=20-13=7\\\\ \left \{ {{y=13} \atop {x=7}} \right.
3D+14G=203(11) use elimination 33D+154G=2233 11D+11G=220(-14) to cancel G -154D-154G=-3080 -121D=-847 divide by -121 on both sides D=7 plug back into equation 11(7)+11G=220 77+11G=220 subtract 77 from both sides 11G=143 divide by 11 on both sides G=13
The cost of one DVD is $7 and the cost of one video game is $13 based on Mike's and Nick's purchases. This was determined by setting up a system of equations and solving for the variables. The values were found through substitution and simplification of the equations.
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