Question

PLEASE HELP IM BEGGING What steps do you use to solve a system of two equations using substitution?

For example:
3b-45c=120
b-3c=10

Answer 1

B is equal to 2.5 and C is equal to -2.5

Explanation:

You would first subtract b-3c from 3b-45c

Your equation would be:

3b-45c-(b-3c)=120-10

Then simplify the equation but distributing the negative sign:

3b-45c-b+3c=110

Then reorder the equation:

3b-b-45c+3c=110

Which equals 2b-42c=110

Then divide both sides by 2:

b-21c=55

b=55+21c

Subsitute 55+21c for b:

3(55+21c)-45c=120

Distribute the 3:

165+63c-45c=120

165+18c=120

Subtract 165 from both sides:

18c=120-165

18c=-45

Divide by 18 for both sides

c= -2.5

To find b, substitute -2.5 for c in the b=55+21c

b=55-52.5

b=2.5

Please correct me if I am wrong.