Chapter 1 - Introduction to Algebraic Expressions - 1.6 Subtraction of Real Numbers - 1.6 Exercise Set - Page 50: 129

$9$

The given description, "the difference between $3.8$ and $-5.2$" translates to \begin{array}{l}\require{cancel} 3.8-(-5.2) .\end{array} Since the expression $a-(-b)$ simplifies to $a+b,$ the expression above simplifies to \begin{array}{l}\require{cancel} 3.8-(-5.2) \\\\= 3.8+5.2 \\\\= 9 .\end{array}