So, standard form basically takes the shape of Ax+By=C. You want all of your variables to be on the left side and your constant on the right. There can also be no fractions!
In your case, since you didn't mention a y value for y, your line is y=-3/2x+6
first we get rid of the fraction by multiplying both sides of the equation by 2:
(2)y= (-3/2x+6)(2) and get
2y=-3x+12
now all there is left to do is get x to the other side by adding it to both sides:
3x+2y=12 is your final answer
In the given question Laura has $30 to spend on food for the week.
According to the question we have to set the inequality between total amount and amount spent on food.
Amount spend by Laura on food for the week = $30
Let the amount spent by Laura on food be x
So she has to spend up to $30
So inequality will be 
So option b is the answer
C equals 17.5 you have to cross multiply to find what c is equal to