Perhaps you should try some spelling variations:
learning inequality » earnings inequality, garding inequality, measuring inequality
learning activity » learning activities
learning ability » learning disability, learning about
wage » wave

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: wage AND ((learning inequality) OR (((learning quality) OR (((learning ability) OR (learning activity)))))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "wage and ((learning inequality) or (((learning quality) or (((learning ability) OR (learning activity))))))".
• Adding a wildcard symbol may retrieve word variants: wage and ((learning inequality) or (((learning quality) or (((learning ability) OR (learning activity))))))*.