Chapter 13 - Counting and Probability - 13.3 Probability - 13.3 Asses Your Understanding - Page 866: 46

$0.1$

We know that by the addition rule of probabilities $P(A\cup B)=P(A)+P(B)-P(A\cap B)$ Substitute the given values into the formula above to obtain \begin{align*} 0.6&=0.25+0.45-P(A\cap B)\\P(A\cap B)&=0.25+0.45-0.6\\ P(A\cap B)&=0.1 \end{align*}