The red button in the first bag is 1*20%=0.2.

The blue button in the second package is 1.5*45%=0.675.

The total amount of the two packages is 1+ 1.5=2.5.

The mixed red button is 2.5*26%=0.65.

Before mixing, the red button in the second bag is 0.65-0.2=0.45.

0.45÷ 1.5= 30% of the total amount of the second package.

Therefore, the proportion of green buttons in the second bag before mixing is as follows

1-45%-30%=25%

The blue button in the first bag before mixing is1* (1-20%-25%) = 0.55.

(0.55+0.675)÷2.5=49%

After mixing, the blue button accounts for 49%.