Question 836704
x = glasses of skim milk
y = servings of meat
1 serving meat is 0.25 pounds meat


The sum x+y has no clear useful meaning in this problem as described.


Account for the iron:  {{{0.3*x+3.75*y=7.17}}}, and you should examine the arrangement of the numbers very carefully to see how the left and right members are milligrams of iron.


Account for the protein:  {{{8.5x+23y=71}}}


Those two equations are your linear system.  Solve for x and y.
Tell if you further trouble with this.