Help with an unusual query

[Darkmatter5]

I have 2 tables

 

grading_system

grademin_score

A90

B80

C70

D60

F0

 

tests

 

test_idscore

182

275

390

495

596

 

 

How can I use the grading_system table to determine the following outcome?  Or how should I better design my grading_system table to accomplish this?

 

Test 1: 82% = B

Test 2: 75% = C

Test 3: 90% = A

Test 4: 95% = A

Test 5: 96% = A

 

Thanks!

[Daniel0]

SELECT t.test_id, t.score,
  (SELECT g.grade
     FROM grading_system AS g
     WHERE g.min_score <= t.score
     ORDER BY g.min_score DESC
     LIMIT 1) AS grade
  FROM tests AS t;