Pg 647 (579) - Q18
The question depends on the statement x + y = 5. This means
that x and y can be any of 4 combinations. If x is 1 and y is 4,
then 4x + 9y is 40. If x is 2 and y is 3, then 4x + 9y is 35.
If x is 3 and y is 2, then 4x + 9y equals 30. Finally, if x is 4
and y is 1, then 4x
+ 9y becomes 25. The four possible answers, therefore, are
25, 30, 35, or 40.