Answer:
<em>(a) x=2, y=-1</em>
<em>(b) x=2, y=2</em>
<em>(c)</em> 
<em>(d) x=-2, y=-7</em>
Step-by-step explanation:
<u>Cramer's Rule</u>
It's a predetermined sequence of steps to solve a system of equations. It's a preferred technique to be implemented in automatic digital solutions because it's easy to structure and generalize.
It uses the concept of determinants, as explained below. Suppose we have a 2x2 system of equations like:

We call the determinant of the system

We also define:

And

The solution for x and y is


(a) The system to solve is

Calculating:





The solution is x=2, y=-1
(b) The system to solve is

Calculating:





The solution is x=2, y=2
(c) The system to solve is

Calculating:





The solution is

(d) The system to solve is

Calculating:





The solution is x=-2, y=-7
One may note, you never quite asked anything per se, ahemm, if you meant simplification.
Answer:
72 kg
Step-by-step explanation:
For concreatting a tower cement, sand, stones are in the ratio 1:2:4 For 144kg sand.. What amount of cement is required?
We are given the ratio
cement: sand:stones
= 1:2:4
The sum of proportion =
1 + 2 + 4 = 7
We are given the kg of sand = 144kg
Step 1
We find the total kg of cement, sand and stones = x
Using the proportion of sand,
2/7 of x = 144kg
2/7 × x = 144kg
2x/7 = 144kg
Cross Multiply
2x = 7 × 144kg
x = 7 × 144kg/2
x = 504kg
Therefore the total kg of cement, sand and stone = 504kg
Step 2
The amount of cement required is calculated as:
1/7 × 504 kg = 72 kg
Therefore, 72kg of cement is required.
Answer: $5
Step-by-step explanation:
i = 50 x .10 x 1
i = 5
8.46...hundredth. 8.5....tenths