why not use real math symbols?
9xy-15yz = 3y(3x-5z)
9xy minus 15yz
2 answers
9xy minus 15yz
= 9xy - 15yz
= 3y(3x - 5z) , not much else can be done
= 9xy - 15yz
= 3y(3x - 5z) , not much else can be done