Hey there!
2a + 4 = 3
ADD 4 to BOTH SIDES
2a + 4 - 4 = 3 - 4
CANCEL out: 4 - 4 because that gives you 1
KEEP: 3 - 4 because it helps solve for the a-value
2a = 3 - 4
3 - 4 = -1
2a = -1
DIVIDE 2 to BOTH SIDES
2a/2 = -1/2
CANCEL out: 2/2 because it gives you 1
KEEP: -1/2 because it gives you the value of the a-value
a = -1/2
SIMPLIFY IT!
Therefore, your answer is: a = -1/2
Good luck on your assignment and enjoy your day!
~Amphitrite1040:)