Question

If x is less than 10, and y is less than 5, it follows that:

A) x is greater than y
B) x = 2y
C) x - y = 5
D) x + y is less than 15

Answer 1

Try them all. D wins.

Answer 2

Answer:
D) x + y is less than 15

x = 1-9
y = 1-4

any number from each category of x and y that add up have sums that are all lower than 15

Answer 3

here is the reason why:

x < 10
y < 5
we can add them just like equations as long as the inequality sign
goes the same way

so let's add them:
x + y < 15