Question

Resolver por metodo de sustitucion, Porfavor.
7x+4y=3
9x+4y=5

Answer 1

7x+4y=3
9x+4y=5

7x=3-4y
x=3-4y/7

9(3-4y/7)+4y=5
27-36y/7 +4y=5
27-36y+28y/7=5
27-36y+28y=35
-36y+28y=35-27
-8y=8
y=8/-8
y=-1

x=3-4y/7
x=3-4(-1)/7
x=3+4/7
x=7/7
x=1

comprobación:
7x+4y=3
7(1)+4(-1)=3
7-4=3
3=3

9x+4y=5
9(1)+4(-1)=5
9-4=5
5=5