diff --git a/ex-4_61-xx.scm b/ex-4_61-69.scm
similarity index 86%
rename from ex-4_61-xx.scm
rename to ex-4_61-69.scm
index 7930ba5..f1d431b 100644
--- a/ex-4_61-xx.scm
+++ b/ex-4_61-69.scm
@@ -131,15 +131,21 @@
 
 (display "\nex-4.69 - greats\n")
 
-; Beginning with the data base and the rules you formulated in exercise 4.63,
-; devise a rule for adding ``greats'' to a grandson relationship. This should
-; enable the system to deduce that Irad is the great-grandson of Adam, or that
-; Jabal and Jubal are the great-great-great-great-great-grandsons of Adam.
-; (Hint: Represent the fact about Irad, for example, as ((great grandson) Adam
-; Irad). Write rules that determine if a list ends in the word grandson. Use
-; this to express a rule that allows one to derive the relationship ((great .
-; ?rel) ?x ?y), where ?rel is a list ending in grandson.) Check your rules on
-; queries such as ((great grandson) ?g ?ggs) and (?relationship Adam Irad).
+(eval-query
+  '(rule (greats ?relation ?parent ?grandson)
+         (and (grandson ?parent ?grandson)
+              (same ?relation (grandson)))))
+
+(eval-query
+  '(rule (greats ?relation ?parent ?grandson)
+         (and (nson ?parent ?son)
+              (greats ?son-relation ?son ?grandson)
+              (append-to-form (great) ?son-relation ?relation))))
+
+(eval-query '(greats ?x Adam Irad))
+(eval-query '(greats ?x Adam Jabal))
+(eval-query '(greats (great grandson) Adam ?ggs))
+(newline)
 
 (display "\nex-4.70\n")
 
diff --git a/ex-4_70-xx.scm b/ex-4_70-xx.scm
new file mode 100644
index 0000000..0368ce8
--- /dev/null
+++ b/ex-4_70-xx.scm
@@ -0,0 +1,7 @@
+(load "util.scm")
+(load "misc/sicp-query.scm")
+
+(initialize-data-base microshaft-data-base)
+
+(display "\nex-4.70\n")
+