Question

3a + b = 1/7
a - b = 3

Answer 1

3a+b=1/7
a-b=3
soma as equações, tirando o mmc entre 7 e 3
4a=22/7
a = 22/7/4
a=22/x4 a= 44/7
44/7-b=3
44/7=3+b
b=44/7-3
b=23/7