Question 1207317
<pre>
Let x = the common number of each color Sally had at the end.

At the beginning she had: 
half as many reds, or 0.5x reds.
twice as many blues, or 2x blues.
30 more greens, or x+30 greens.
20 fewer purples, or x-20 purples.

So

{{{0.5x + 2x + x+30 +x-20 =1153}}
{{{4.5x+10=1153}}}
{{{4.5x=1143}}}
{{{x=254}}}

At the beginning she had: 
0.5x = 0.5(254) = 127 reds.
2x = 2(254) = 508 blues.
x+30 = 254+30 = 284 greens.
x-20 = 254-20 = 234 purples.

Edwin</pre>