Well a half cup is 2/4 and if the serving size is 3/4 there is only 66.66% of the serving size needed hope this helps!
Let m and j be the current ages of Matthew and Jenny, respectively.
Now, Matthew is 3 times as old as Jenny, so the variables are in the following relation:

In 7 years, both of them will be 7 years older, i.e. their ages will be m+7 and j+7, and Matthew will be twice as old:

Now, remembering that m=3j, we can rewrite the second equation as

So, Jenny is 7 and Matthew is 21 (he's 3 times older).
In fact, in 7 years, they will be 14 and 28, and Matthew will be twice as old.
Okay I get some of them, your first one - 1 I disagree with. So we can solve with two points by using a equation y2-y1 over x2-x1. So it's 4-8 over - 3-6 with the numerator being - 4 and the denominator being - 9. Any questions on how to solve for slope with two coordinates.
Theres not enough information to properly answer this.