7. jack and max share some counters. jack has 3 times as many counters as max.
(a) write down the ratio of the number of counters jack has to the number of counters max has.
(b) what fraction of the counters does max have?

To answer this item, we let x be the number of counters that Max has. By the representation, the number of counters that Jack has is 3x. 

a. Ratio of counters,
                               3x:x 
which can be simplified by dividing by x both sides of the ratio giving us the answer of, 
                               3:1

b. Fraction of counters Max have,
                                fraction = x / (x + 3x) = 1/4

Observation of mass