-15
Step-by-step explanation
Step 1
let x represent the number
now, traslate into math terms
a)six more than a number is negative nine
hence, we got the equation
Step 2
now, solve the equation
we need isolate x without affect the expression, The subtraction property of equality tells us that if we subtract from one side of an equation, we also must subtract from the other side of the equation to keep the equation the same
hence, subtract 6 in both sides
therefore, the number is -15
I hope this helps you