4 balloons = 2/8 of a smile
____ balloons = 2/4 of a smile
4 balloons = 0.25 of a smile
8 balloons = 0.5 of a smile
4 balloons = 2/8 of a smile = 1/4 of a smile
you want to find 2/ 4 of a smile....tiwce as much = 8 balloons