Question 189687
Let 

x = amount invested at 4%

y = amount invested at 5%




Since $6,300 is invested, this means that {{{x+y=6300}}}. Solve for "y" to get {{{y=6300-x}}}



Also, because we want the simple interest in both investments to be equal, this means that {{{0.04x=0.05y}}}. Multiply both sides by 100 to get {{{4x=5y}}}



{{{4x=5y}}} Start with the second equation.



{{{4x=5(6300-x)}}} Plug in {{{y=6300-x}}}



{{{4x=31500-5x}}} Distribute.



{{{4x+5x=31500}}} Add {{{5x}}} to both sides.



{{{9x=31500}}} Combine like terms on the left side.



{{{x=(31500)/(9)}}} Divide both sides by {{{9}}} to isolate {{{x}}}.



{{{x=3500}}} Reduce.



So $3,500 needs to be invested at 4%



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{{{y=6300-x}}} Go back to the first equation



{{{y=6300-3500}}} Plug in {{{x=3500}}}



{{{y=2800}}} Combine like terms.



So $2,800 is needed to be invested at 5%