The area of a parallelogram is given by the formula
A= h * b
where A is area , b is the base length
Given in question that ;
A= 120 units squared and h is 12 units then the base b will be;
A= h*b
120 = 12 * b
120 =12b
Divide both sides by 12 to get b as
120/12 = 12b/12
10 = b
The answer is : b= 10 units.