Question 838759
Let the three amounts be A, B, and C.
1.{{{B=2C}}}
2.{{{A+B+C=4950}}}
{{{4*A/100+10*B/100+15*C/100=520}}}
3.{{{4A+10B+15C=52000}}}
When you substitute eq. 1 into eqs.2 and 3, you end up with only 2 variables (A & C).
{{{A+2C+C=4950}}}
4.{{{A+3C=4950}}}
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{{{4A+20C+15C=52000}}}
5.{{{4A+35C=52000}}}
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Now solve for A and C and go back to eq. 1 to solve for B.
Repost if you still need help.