SOLUTION: Find the solution to each system by the addition (elimination) method. Check your answers. 4s-5t=18 6s+10t=-8

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Question 536511: Find the solution to each system by the addition (elimination) method. Check your answers.

4s-5t=18
6s+10t=-8

Answer by Maths68(1474) About Me  (Show Source):
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4s-5t=18.........(1)
6s%2B10t=-8...........(2)
Take (2)
6s%2B10t=-8
2%283s%2B5t%29=-8
Divide by 2 both sides
2%283s%2B5t%29%2F2=-8%2F2
3s%2B5t=-4...............(3)
Add (1) and (3)
4s-5t=18
3s%2B5t=-4
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7s=14
Divide by 7 both sides
7s%2F7=14%2F7
s=2
Put the value of s in (1)
4s-5t=18.........(1)
4%282%29-5t=18
8-5t=18
-5t=18-8
-5t=18-8
-5t=10
Divide by -5 both sides
-5t%2F-5=10%2F-5
t=-2
(s,t)=(2,-2)

Check
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Put the values of x and y in (2)
6%282%29%2B10%28-2%29=-8
12-20=-8
-8=-8