Al dividir (x^2-9/x^2+2x-3) / (x^2+6x-27/x^2-10x+9) se obtiene: a x/x+9 b x-9/x+9 c x+9/x-9 d 9/x-9

We have the following expression:
 (x ^ 2-9 / x ^ 2 + 2x-3) / (x ^ 2 + 6x-27 / x ^ 2-10x + 9)
 Let's rewrite the expression:
 (((x-3) * (x + 3)) / ((x + 3) * (x-1))) / (((x + 9) * (x-3)) / ((x-9) ) * (x-1)))
 We cancel similar terms:
 (1/1) / ((x + 9) / (x-9))
 Doing double c we have:
 (x-9) / (x + 9)
 
 B x-9 / x + 9

1. 0.3 •4 is the same as 4 groups of 0.32. 7•0.8 is the same as 7 groups of 0.83. it increases by 0.5 every time, so 0.5x4 it increases by 0.9 every time, so 0.9x5. 0.9•12=10.86. 0.47•5=2.35i can finish the next ones in a separate post