The book is Hamilton's Essentials of Arithmetic -- Higher Grades,
by Samuel Hamilton, PhD, LLD, Superintendent of Schools, Allegheny County, Pennsylvania.
Published by American Book Company (New York, Cincinnati, Chicago, Boston, Atlanta), 1919 and 1920.

My father used this textbook when he was in the 7th grade in Fort Lauderdale, Florida, about 1926.
I think you will agree that the math 7th graders were expected to master in his time was much
more practical and required a greater depth of understanding than our the modern math
taught in our modern schools.

From the Preface:

"The two important ends sought in the teaching of arithmetic are
(1) to give the pupil a mastery of number combinations and processes
as will enable him to perform with accuracy and speed all common numerical operations;
and (2) to train him in the skillful application of these processes to the problems
that he is likely to meet in his daily experiences."

Dad wrote in the front:

Henry W. Sander
Central School
Grade 7, Section 4
Fort Lauderdale, Fla.

Also,

Henry Walker Sander
Central School
Grade 7

Grade 7 probably occurred when he was about 13 years old,
so I suppose this was his book in about 1926.

I scanned in two pages from the middle of the book.
Note that the problems are pretty interesting and practical,
and require a higher level of mathematical understanding
than is typical in most 7th graders in our day.