Let N be the number we seek. Let's translate the words into math.
35 less than -35
half a number 1/2 N
equals 14 = 14
Now we put it together with a plus sign between the first two parts. No sign is needed between the second and third, as an equals sign is there.
-35 + 1/2 N = 14
We clear fractions at this point and multiply the whole equation by 2. We choose 2 because it's the lowest common denominator of 1, 2, and 1.
-70 + N = 28
N = 98 <---- add 70 to both sides.
Thus the mystery number is 98.