Translate the following into an equation: the product of a number and -3 increased by 4 is 12

If you would like to transform the following phrase into an equation, you can do it like this:

the product of a number and -3 increased by 4 is 12
a number ...n
the product of a number and -3 ... n * (-3)
increased by 4 ... + 4
is 12 ... = 12

Now you just have to put this together: n * (-3) + 4 = 12

If you want to solve the equation, you can do it like this:
n * (-3) + 4 = 12
-3 * n = 12 - 4
-3 * n = 8
n = 8 / (-3)
n = - 8/3 = - 2 2/3