Build an equation from this phrase.
"The sum of a number and 12..." The word sum is the keyword of what operation we are doing. We are doing addition. When we continue the phrase we know we are adding a number (an unknown) and 12.
So, on the left-hand side we have x + 12.
"... is 20" In mathematics, the word 'is' can mean equal. So, the left-hand side will equal the number 20.
Now we have the equation x + 12 = 20.
Solve for x.
x + 12 = 20
x = 8 <-- Subtract each side by 12
So, x is equal to 8.
