Answer:
when x = 39.25, y = 2.75
when x = 2.75, x = 39.25
Step-by-step explanation:
use substitution method
x+y = 42 ------ (1)
xy = 108 ------ (2)
from (1) ,
x+y = 42
y = 42-x ------ (3)
substitute (3) into (2)
xy = 108
x( 42-x ) = 108
42x - x² = 108
-x² + 42x - 108 = 0
x² - 42x + 108 = 0
use the following formula to solve the value of x:

a = 1
b = -42
c = 108














the 2 values of x are x = 39.25 and x = 2.75
substitute x = 39.25 into (3)
y = 42-x
y = 42-39.25
y = 2.75
substitute x = 2.75 into (3)
y = 42-x
y = 42-2.75
y = 39.25
when x = 39.25, y = 2.75
when x = 2.75, x = 39.25