Answer:
-5
Step-by-step explanation:
 
        
             
        
        
        
Step-by-step explanation:
To determine simple interest, we use the formula

 where I is the interest, p is the principal or initial amount, r is the interest rate is in the unit of years and t is the time in years
When the times is 3 years , then we plug in 3 for 't' directly

we know that 1 year = 12 months
Suppose, the time is given in months then we divide time 't' by 12
When the times is 4 months , then we plug in 4 for 't' and divide by 12

we know that 1 year = 365 days
Suppose, the time is given in days then we divide time 't' by 365
When the times is 45 days , then we plug in 45 for 't' and divide by 365

 
        
             
        
        
        
Step-by-step explanation:
6x-12=x+3
6x-x=3+12
5x=15
x=15/5
x=3
 
        
                    
             
        
        
        
Answer:

Step-by-step explanation:
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Given:

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Combine like terms.

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Add 12 to both sides.

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Divide both sides by 9.

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Hope this is helpful.
 
        
             
        
        
        
Answer:
x = -2, y = -4
coordinate: (-2, -4)
Step-by-step explanation:
Given system of equations:
a) 4x - 7y = 20
b) x - 3y = 10
1. Make x the subject in the <em>second</em> equation:
⇒ x - 3y = 10 [add 3y to both sides]
⇒ x - 3y + 3y = 10 + 3y 
⇒ x = 3y + 10
2. Substitute the given value of x into <em>first</em> equation:
⇒ 4x - 7y = 20
⇒ 4(3y + 10) - 7y = 20 [distribute 4 through the parentheses]
⇒12y + 40 - 7y = 20 [combine like terms]
⇒ 5y + 40 = 20 [subtract 40 from both sides]
⇒ 5y - 40 - 40 = 20 - 40
⇒ 5y = -20 [divide both sides by 5]
⇒ 5y ÷ 5 = -20 ÷ 5
⇒ y = -4
3. Find the value of x by substituting the given value of y into x = 3y + 10:
⇒ x = 3y + 10
⇒ x = 3(-4) + 10 [multiply]
⇒ x = -12 + 10 [add]
⇒ x = -2
4. Check your work:
<em>a) 4x - 7y = 20</em>
⇒ 4(-2) - 7(-4) = 20
⇒ -8 + 28 = 20
⇒ 20 = 20 ✔
<em>b) x - 3y = 10</em>
⇒ -2 - 3(-4) = 10
⇒ -2 + 12 = 10
⇒ 10 = 10 ✔
This system of equations has a solution at (-2, -4).
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