Answer:
Emily is solving the following system of equations using substitution:
y = 3x - 4
y = 2x + 1
<u>Part</u><u> </u><u>A</u><u>:</u>
After substituting y's values:
3x - 4 = 2x + 1
<em><u>What she did:</u></em>
3x - 4 = 2x + 1
3x + 2x - 4 = 1
5x - 4 = 1
<em><u>What she should have done:</u></em>
3x - 4 = 2x + 1
3x - 2x - 4 = 1
x - 4 = 1
<u>Part</u><u> </u><u>B</u><u>:</u>
This rule has not been followed: Sign changes when numbers shift from left to right of ' = 'sign.
Emily did not changed the sign of the number, 2x from + 2x to - 2x when it was moved from the right side to the left.
