A dog eats 7 cans of food in 3 days. At this rate, how many cans of food does the dog eat in 3 + d days? the answer is 7 + 7d/3 but I don't know how to get to that.
7 cans --------------------- 3 days x cans ---------------------- 3 + d days ----------------------------------------------- We will make a proportion: 7 : x = 3 : ( 3 + d ) or: 7 / x = 3 / ( 3 + d ) / Then we will cross multiply. 7 * ( 3 + d ) = 3 x 21 + 7 d = 3 x x = ( 21 + 7 d ) : 3 x = 7 + 7d/3 ( and this is your answer ).
