### Home > INT1 > Chapter 7 > Lesson 7.1.1 > Problem7-11

7-11.

Solve the systems of equations below.

Read the Math Notes box in Lesson 6.2.3 to review the Substitution Method. Use it to solve both parts.

1. $y = 3x$
$2y - 5x = 4$

To start part (a) substitute $3x$ in for $y$ into the second equation $2y − 5x = 4$. So $2(3x) − 5x = 4$.

Solve for $x$.

Once you solve for $x$, substitute that value in for $x$ into one of the original equations: $y = 3x$ or $2y − 5x = 4$.
Solve for $y$.

Put the answer in point form $(x, y)$.
The final answer is $(4,12)$.

1. $x - 4 = y$
$-12 = 3y - 3x$

Substitute ($x − 4$) in for $y$ in the second equation
$-12 = 3(x-4) − 3x$.

Follow steps $2$ and $3$ from part (a).

Read the Math Notes box in Lesson 6.4.1 to review the different types of solutions for systems of equations.