Solving the equations by the substitution method we find that the values for X are: 5 and -4.
How to solve a system?
To solve a system it is necessary to find the values that satisfy all the equations simultaneously. A system is called 1st degree when the greatest exponent of the unknowns, which integrate the equations, is equal to 1 and there is no multiplication between these unknowns.
So using the substitution method we have:
[tex]3x+20= x^2+2x\\0= x^2+2x-3x-20\\0= x^2-X-20\\(X-5)(X+4)\\X-5=0\\X=5\\X+4=0\\X=-4[/tex]
See more about system at brainly.com/question/9061107
