University of South Carolina High School Math Contest/1993 Exam/Problem 7
Problem
Each card below covers up a number. The number written below each card is the sum of all the numbers covered by all of the other cards. What is the sum of all of the hidden numbers?
![$\mathrm{(A) \ }4.2 \qquad \mathrm{(B) \ }5 \qquad \mathrm{(C) \ }5.6 \qquad \mathrm{(D) \ }6.2 \qquad \mathrm{(E) \ }6.8$](http://latex.artofproblemsolving.com/b/9/e/b9ea45696aca89b031c2973ecfc5f973ace67524.png)
Solution
If we call the squares (in order from left to right), we have:
,
,
,
,
,
.
Adding all the equations gives us
.