The question doesn’t say if it’s simple or compound interest. If it’s compound interest we need to know the period (annually, quarterly, monthly, daily, continuous, etc.).
Let’s assume simple interest. So after 16 years the interest would be 184803×16×3.7/100=$109403.38 and the amount owing would be $294206.38.
For the remaining 14 years the interest is 294206.38x14×1.2/100=$49426.67. This brings the total amount of the loan to $343633.05, and the total interest is 343633.05-184803=$158,830.05. (This is the same as adding the two interest amounts together: 109403.38+49426.67=158830.05.)