Test 2 Section 5 - #15 (page 468)

This one has hints of PLUGiIN and BACKSOLVE, even though it's a grid-in! We don't need any of that stuff about how many candies are in the jar...that's just extraneous information. All we need to know is where Ari's starting from (3 red, 4 green) and how many more he takes. We want him to have more red pieces than green pieces by the end, but just barely. Here's how I set it up:

34This is our starting point.
+7+6Just plugging in 2 numbers that are close together and add up to 13.
=10=10OOPS!  That's not enough red...Ari has the same amount of each color now.

Now it's kinda clear where to go: add one more red (and one less green):

34This is our starting point (again).
+8+5Plug in new numbers.
=11=9That'll do it!  Any less red and he'd have the same number of each (as we saw above).