Let's look at it like this:
5/10+1/5 = (5/10) + (1/5)
5/10 = 0,5
1/5 = 0,2
so it's 5/10 + 1/5 = (5/10) + (1/5) = 0,5 + 0,2 = <u>0,7 </u>
20
4/9 of 36 is 16 so that leaves 20 that aren’t chocolate
0.75$
0.75$
0.75$
0.75$
0.75$
0.75$
0.75$
+
----------
5.25$
v
13.25$ - 5.25$ = 8.00$
Since there's 8.00$ left, and there's fours pens, 8 / 4 = 2.00$
A pen cost 2.00.