Question 953643
You need a column for question #1, 115,120,110.  Try to set up the system of equations first, if that will help you arrange all the necessary elements.


Initially, E1 is for zince E2 for potassium, E3 for Radium.


20, 20, 20, 115
30, 50, 10, 10
15, 10, 10, 110


Try starting with some work between E2 and E3.  Subtract half of E2 from one of E3 and revise E3....


Every element can be divided by 5 and you get this matrix:


4, 4, 4, 23
3, 5, 1, 1
3, 2, 2, 22


( <s>I did not yet take further steps with the matrix</s>).


I worked through the matrix, and find Pears, {{{27/16}}},   Oranges, {{{-103/16}}}.   I'm with you.  Negative number cannot happen.  Problem description is bad.
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Final matrix was of this form:
4,4, 4, 23
0, 8, -8, -65
0, 0, 1, 27/16