Easiest
Easy
Medium
Hard
Challenging
100

1/5 + 1/5

2/5

100

2/5 + (-1/5)

1/5

100

1/2 + 1/4

3/4 (6/8)

100

2/3 + 1/4

11/12

100

-11/12 + 2/3

-1/4 (-9/36)

200

2/7 + 2/7

4/7

200

4/7 + (-2/7)

2/7

200

3/5 + 2/10

4/5 (8/10, 40/50)

200

-2/5 + 4/9

2/45

200

7/9 + 1/5

44/45

300

9/11 - 7/11

2/11

300

-2/9 + 3/9

1/9

300

2/3 - 1/6

1/2 (3/6, 9/18)

300

-5/6 + 3/8

-11/24 (-22/48)

300

1/12 - (-5/6)

11/12 (66/72)

400

15/17 - 9/17

6/17

400

5/9 - (-2/9)

7/9

400

-1/4 + 1/8

-1/8 (-4/32)

400

8/9 - 5/12

17/36 (51/108)

400

11/12 - 5/8

7/24 (28/96)

500

18/29 + 7/29

25/29

500

-3/11 + (-5/11)

-8/11

500

-2/9 - (-1/3)

1/9 (3/27)

500

9/12 - 2/5

7/20 (21/60)

500

-6/11 - (-2/9)

-32/99