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Question
Solve the following pair of linear (simultaneous) equation by the method of elimination by substitution:
1.5x + 0.1y = 6.2
3x - 0.4y = 11.2
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Solution
The given pair of linear equations are
1.5x + 0.1y = 6.2 ...(1)
3x - 0.4y = 11.2 ...(2)
equation (1) dividing from 10
`(1.5x)/10 + (0.1"y")/10 = 6.2/10`
⇒ 15x + y = 62
y = 62 - 15x ...(3)
Putting the value of y from in equation (2)
`3x - 0.4(62-15x) = 11.2`
⇒ `(30x-4(62-15x))/10=112/10`
⇒ 30x - 248 + 60x = 112
⇒ 90x - 248 = 112
⇒ 90x = 360
⇒ x = 4 ...(4)
Substitute the value of x from equation (4) in equation (3)
y = 62 - 15x
= 62 - 15(4)
= 62 - 60
⇒ y = 2
∴ Solution is x = 4 and y = 2.
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