Using simultaneous equation,
a=-1, b=1, x=1, y=0
OR
a=1, b=-1, x=1, y=0.
The percent change of 13.7 to 40.2 is 193.4%
To find percentage change, you need to find the difference between the two numbers. In this case, 26.5.
You then divide 26.5 by 13.7 and move the decimal point two spaces to the right.
Answer: 
Step-by-step explanation:
See attached image.