To translate this sentence into an equation, let's translate each part separately.
"Six times a number"
Let the unknown number be x.
Six times x means 6 multiplied by x:
6x
"Nine subtracted from six times a number"
Substituting what is known:
"Nine subtracted from 6x"
That is,
6x - 9
And finally,
"Nine subtracted from six times a number is -177"
Substituting what is known:
"6x - 9 is -177"
That is,
6x - 9 = -177
Thus,