Question 194164
1)  x^2 +y^2 =25
2)  x-2y=-5,,,,,,x = 2y-5
subst
(2y-5)^2 + y^2 = 25
4y^2-20y+25 +y^2 -25 = 0
combining  like  terms
5y^2  -20y = 0 
y ( 5y-20) = 0
y=0,,,,,,5y-20=0,,  y = 4
subst  in  x =2y-5
x=-5,,,,,x=3
(-5,0),,,,,and  (3,4)

checking
(-5,0)  in 2)  (-5)-2(0) = -5,,,ok
in 1) (-5)^2 +(0)^2 = 25,,,,,ok
,
( 3,4),,  in  1)  (3)^2 + (4)^2 = 25   ,,,,,,,ok
in 2)  (3) - 2 (4) = -5,,,ok