For the first question, all you need to know is that the (amount you want) divided by (the amount of cards total) is the probability of getting the amount you want at random. for example, if there are 3 red marbles in a bag of ten marbles, you divide 3 by 10 (0.30) the probability of picking up a red marble is 30%. try adding up how many cards you want to pick up by the number of cards total.
150g/12cakes
150/12 = 12.5
12.5g/cake
12.5x30 = 375
Therefore, you need 375g for 30 cakes.
90/36 is 2.5, so the Baker needs to make 2.5 batches of cookies
2.5 batches of cookies x 2.25 cups of flour
is 5.625 cups of flour
which is 5 5/8 cups of flour
You haven't provided the required roots, but I can tell you how to do this kind of exercises in general.
If the 
coefficient is 1, i.e. the equation is written like 
, then you can say the following about the coefficients b and c:
is the opposite of the sum of the roots
is the multiplication of the roots.
So, for example, if we want an equation whose roots are 4 and -2, we have:
So, the equation is 
If your roots are rational, you can work like this: suppose you want an equation with roots 3/4 and 1/2. You have:
And so the equation is
In order to have integer coefficients, you can multiply both sides of the equation by 8:
15, 28, 41.
add the common difference to each consecutive term to find the next term in the sequence.
2+ 13= 15
15+ 13= 28
28+ 13= 41
