Question

Can you show the steps and answer to the following problem?

Solve the system of equations by substitution.
N_(Q) - 2ND = 11
3N_(Q) + N_(D) = -2

Answer 1

Start by solving one of the equations for one variable in terms of the other variable. It doesn't matter which equation or variable--try to pick an easy one:
Nq - 2Nd = 11
Nq = 11 + 2Nd

Now substitute that value into the other equation and solve:
3Nq + Nd = -2
3(11 + 2Nd) + Nd = -2
33 + 6Nd + Nd = -2
7Nd = -35
Nd = -35/7

Now plug that into any of the previous equations to solve for the other variable:
Nq = 11 + 2Nd
Nq = 11 + 2(-35/7)
Nq = 11 - 10
Nq = 1