Please answer this correctly

According to the general equation for conditional probability if p(anb)=3/7 and p(b)=7/8 what is p(a i b)

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Jo divides a candy bar into eight equal pieces for her children to share she gives three pieces to sam three pieces to leslie and two pieces to margie rose the two month old baby does it doesn't get any what fraction shows how muchw candy each of the four children got. what's the answer to my question