first what quantities do we need to talk about?
the problem speaks of “a number”, let’s call that number x.
now write the equation that relates x to the other numbers we know.
the first clue is the word “difference”.
this means “subtraction”, but we need to subtract something from something else.
what are the two somethings? ”a number times 7” and “4”.
so, since we have a name for “a number”, let’s translate this as x*7 - 4 what else do we know?
it says the difference is 9. So complete the equation x*7 - 4 = 9 if we rewrite this cosmetically, 7x - 4 = 9
i assume that you know how to solve this for x.
so then wehn solving 7x - 4 =9 we take -4 change it to +4 so then +9 we go and get 13
7x = 13
7/7 = 13/7
x= 13/7
