15.
Since every answer has a full row of `3` counters, every column must have at least one counter. So `(A)` is eliminated.
The number of counters in a grid can be counted by rows or by columns.
Consequently the total of all `3` rows must match the total of all `3` columns.
This rules out `(B) 6 ƒ= 5, (C) 7 ƒ= 6, and (D) 87`.
This only leaves `(E)`, which can only be filled in one way, as shown here,
Answer: `(E)`
16.
Since the weight is between `25` kg and `30` kg, four "extra `5` kg" amounts are required.
The total cost is:
`24 + 4 × 8 = 24 + 32 = 56` (dollars)
Answer: `(C)`
Cho mình xin hay nhất nha bạn!!!
@Drew Mclntyre
