Connor can buy 2 kiwis and have a remaining $10
(6×5) + (6×2) = 6×7
It works if you think about it like this:
5 sixes + 2 sixes = (5 + 2) sixes = 7 sixes
This is an example of the <em>distributive property</em>.
To put it simply, we're applying the same multiplication (×6) to two different things which are being added together (5+2).
Here's another example of the distributive property:
2×(3+4) = 2×3 + 2×4