The phrase you typed can be written in mathematical form using a replacement of "a number" with the letter "x" (for our unknown).
So we can translate in mathematical form as shown below:
"four more than the product of a number and 3 equals 7"
x * 3 + 4 = 7
and of course we can solve this equation by operating with thenumbers so as to isolate the unknown "x"on one side of the equal sign:
Subtract 4 from both sides:
x * 3 = 7 - 4
x * 3 = 3
Divide both sides by 3 (so as to eliminate the factor 3 multiplying x):
x = 3 / 3
x = 1
And our answer is that the unknown number is 1 (one).