Answer:
<em>She invested 1600 at 8% (to get the shown $160 interest)</em>
<em>and $7400 at 10% (to get the shown 640 interest)</em>
<em>If x = 4000 then $80 interest is x2 again = $160</em>
<em>and so forth $320 interest x 2 again = $640</em>
Step-by-step explanation:
<em>The format would always be for x and then where </em>
<em>investment - x = interest we can work out totals this way and find x.</em>
<em>9000-x = 800 is first equation and substituted into 2nd equation;</em>
<em>0.10x+0.08(9000−x)=800</em>
<em>Use the distributive property to multiply 0.08 by 9000−x.</em>
<em>0.10x+720−0.08x=800</em>
<em>Combine 0.10x and -0.08x to get 0.02x.</em>
<em>0.02x + 720 = 800</em>
<em>Subtract 720 from both sides.</em>
<em>0.02x=800−720</em>
<em>Subtract 720 from 800 to get 80.</em>
<em>0.02x=80</em>
<em>Divide both sides by 0.02.</em>
<em>x= 80 / 0.02</em>
<em>Make decimals numbers = 1 or above.</em>
<em>80 / 0.02 x 100</em>
<em>x= 8000 / 2</em>
<em>x = 4000</em>