Answer:
1.5 or infinite
Explanation:
For the second one, 8x+4=16, suppose x is 1.5 (1 1/2), then 8x1.5 is 12, then 12+4 is 16.
As for the first one, their is infinite possibilities. If x equals 3 and y is 2, then 8x3=24 and 4x2=8, and 24-8=16. Another example is if x equals 4 and y is 4. Then 8x4=32 and 4x4=16, then 32-16=16. And one final example to make sure you understand. X equals 10 and y equals 20. 8x10=80 and 4x16=64, then 80-64=16.