I=3*C and C=10/3*N and I+C+N=43... solve for C
I=3*C and C=10/3*N and I+C+N=43... solve for C
Well, let's try a method called substitution. Since I=3C, I+C+N=43=3C+C+N (all we did was put 3C in the place of I since I=3C)
So 3C+C+N=4C+N=43, but C=10/3*N, to get N by itself we multiply both sides by 3/10 so 3/10*C=N
Using substitution again, 4C+3/10*C=43. Solve that for C.