Multiply both sides of the equation by
As wonderboy1953 said multiply both sides by 1.06^3 then simplify the expressions..
Then you have 1.06²x+1.06*0.8x+0.64x=33789.12392
you can write 1.06 as 53/50
so we get:
(53/50)²x+212x/250+16x/25=33789.12392
2809x/2500+212/250x+16x/25=33789.12392
(2809x+2120x+1600x)/2500=33789.12392
6529x/2500=33789.12392
x=33789.12392*2500/6529
x=12940
Hope this helped!