This expression, 1.5p + 3p + 2.5p, will represent the amount of money received when p people buy one of each food item.
Since the price of each is the coefficient for p, this will represent how much money will be gained from each food item. All 3 terms will be added together to represent the total amount of money gained from selling all 3 items.
Well your question is a little unclear but say there is a bag of marbles containing 3 green marbles and 6 blue marbles then if you wanted to find the ratio of the green marbles it would be 3/9 or 1/3
1 in 6 chance Mary picks the red marble in the first place. After this there is a 1 in 5 chance her sister picks the blue one. 5 multiplied by 6 is 30.
