Solve the simultaneous equations;5x +y = 21 and x-3y=9

Two ways of doing this, substitution and elimination. Could teach both so students choose which they prefer
Substitution;change the second equation into x=3y+9 then substitute it into the first equation where there's an 'x'. Expand and simplify and substitute your x value to work out the y value

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Answered by Kameel O. Maths tutor

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