Monifer used substitution to solve this system of equations. which equation could be the result of her first step? 3a +b=225 b=a-15

Step-by-step explanation:

The given system of equations are:

                                        (1)

and                                        (2)

Now, substituting the value of b from equation (2) in equation (1), we get

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Again, substituting the value of a=60 in equation (2), we get

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step-by-step explanation: