add the two equations together
5a+5b=25
-5a+5b=35
------------------
0 + 10b =60
divide by 10
b=6
5a + 5b = 25
5a +5(6) = 25
5a +30 =25
subtract 30 from each side
5a =-5
divide by 5
a = -1
Answer (-1,6)
or a=-1 b=6
8.8m questions
11.4m answers