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How do you solve x=2y+7 and x=Y+4 using substitution?

Use substitution to solve the system of equations

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Shelly J. | Excellent Maths Tutoring for academic successExcellent Maths Tutoring for academic su...
5.0 5.0 (240 lesson ratings) (240)
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x=2y+7  equation 1
 
x=y+4
y=x-4  equation 2
 
substitute the value of y in equation 1
 
x=2(x-4)+7
x=2x-8+7
x=2x-1
x=1
 
substitute the value of x in equation 2
 
y=1-4
y=-3
 
 
Amarjeet K. | Professional Engineer for Math and Science TuroringProfessional Engineer for Math and Scien...
4.6 4.6 (8 lesson ratings) (8)
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Substitute x from first equation into second
 
2y + 7 = y + 4
 
y = 4 - 7 = -3
 
Substitute value of y into first equation
 
x = 2(-3) + 7
 
x = -6 + 7 = 1
 
:)