Question

The sum of two numbers is 12.43 and their
difference is 117.77. What are the numbers?

Answer 1

x+y = -12.43
...
x-y = 117.77
..
add the two equations
2x=105.34
/2
x=52.67
...
plug value of x in first equation
52.67+y=-12.43
-52.67
y=-12.43-52.67
y = -65.10