system of equations
c-3d=27
4d+10c=120
3 answers
systems of linear equations by substitution. I need help, I am stuck
x=4
y=5
y=5
so if the equations involve c and d, what are x and y?
The first equation says
c-3d = 27
so,
c = 3d+27
Use that in the other equation:
4d+10c=120
first, divide by 2 so you can work with smaller numbers:
2d+5c = 60
Now, since c = 3d+27, that means
2d+5(3d+27) = 60
2d+15d+135 = 60
17d = -75
d = -75/17
c = 3d+27 = 3(-75/17) + 27 = 234/17
yucky answers, but hey - they're just numbers, eh?
The first equation says
c-3d = 27
so,
c = 3d+27
Use that in the other equation:
4d+10c=120
first, divide by 2 so you can work with smaller numbers:
2d+5c = 60
Now, since c = 3d+27, that means
2d+5(3d+27) = 60
2d+15d+135 = 60
17d = -75
d = -75/17
c = 3d+27 = 3(-75/17) + 27 = 234/17
yucky answers, but hey - they're just numbers, eh?