# Solve the Linear Equations

#### Lalitha183

I tried to solve the equations in different ways but unsuccessful. Kindly someone solve this :

If $a, b, c$ and $d$ satisfy the equations

$a + 7b + 3c + 5d = 16$

$8a + 4b + 6c + 2d = âˆ’16$

$2a + 6b + 4c + 8d = 16$

$5a + 3b + 7c + d = âˆ’16$

Then $(a + d)(b + c)$ equals to ?

#### skipjack

Forum Staff
The equations are satisfied by a = c = -2, b = d = 2.

#### Lalitha183

The equations are satisfied by a = c = -2, b = d = 2.
I want to know how to solve these... Please let me know the steps.

#### Lalitha183

The equations are satisfied by a = c = -2, b = d = 2.
I got $b$ value as $2$ but after that where to put this value to get another variable value ?

#### Denis

Math Team
I want to know how to solve these... Please let me know the steps.
Google "solving 4 unknowns with 4 equations"

Can't teach from here...no blackboard