Question 145486
Pounds of extra lean: {{{x}}}
Pounds of regular: {{{30}}}
Total weight of hamburger after the mixture has been made: {{{x+30}}}


Weight of the fat in the extra lean: {{{0.07x}}}
Weight of the fat in the regular:  {{{0.15*30=4.5}}}
Weight of the fat in the total: {{{0.10(x+30)}}}


The weight of the fat in each of the components of the mixture must add up to the weight of the fat in the total mix, so:


{{{0.07x+0.15(30)=0.10(x+30)}}}.  Just solve for {{{x}}} to get your answer.