Twice the sum of a number x and 9 is equal to 12 less than the number x.  What is the value of x?

x = -30

Step-by-step explanation:

Let x be the number.

2(x + 9) = x - 12

Use distributive property of multiplication

2x + 18 = x - 12

Simplify by combining like terms

2x - x = -12 - 18

x = -30

15

step-by-step explanation:

we are given the following expression and we are to solve it and find the product:

-13 × (-5)

solving the given expression in the standard order of solving a mathematical expression, beginning with the opening of brackets and then multiplying the terms and changing their signs.

-3 × -5 = 15 (answer is positive because when negative is multiplied with negative, it gives a positive answer)

because linear equations are a lot simpler than quadratics equations, and linear equations formula is a lot easier to memorize. that's why i think they're harder.