Answer
$3x-5=7$
Work Step by Step
"Less than" tells us we are going to subtract. In the absence of commas "5 less than" tells us to subtract 5 from whatever follows.
"3 times a number" means to multiply a number by 3, which can be written as 3x.
"Gives" tells us to put an equal sign between the expressions before and after the word "gives".
