# Chapter 1 - Introduction to Algebraic Expressions - 1.7 Multiplication and Division of Real Numbers - 1.7 Exercise Set: 50

$30$

#### Work Step by Step

The product of two numbers with opposite signs is negative while the product of two numbers with the same sign is positive. Multiplying the numbers from left-to-right, then the given expression, $-3\cdot(-5)\cdot(-2)\cdot(-1)$, simplifies to \begin{array}{l} 15\cdot(-2)\cdot(-1) \\\\= -30\cdot(-1) \\\\= 30 .\end{array}

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