Answer:
Below in bold.
Step-by-step explanation:
Standard form is Ax + By = C
where A, B and C are integers and A must be positive.
So the first 2 are already in standard form but the last 2 can be converted to standard form by multiplying each term by -1:
-12x+3y=27
= -1*-12x + -1*3y = -1*27
12x - 3y = -27 is the answer.
The last one is:
24x + 12y = -60.
