A rectangle has a length of 4 inches and area of 12 in.² what is the perimeter of the rectangle

Can someone answer this question for me

1. ∠1 is complementary to ∠2 and ∠3 is complementary to ∠2. subtraction property of equality 2. m∠1 + m∠2 = 90 and m∠3 + m∠2 = 90 substitution 3. m∠1 + m∠2 = m∠3 + m∠2 definition of complementary 4. m∠1 = m∠3 given

In a rectangle klmn, km = 6x + 16 and ln = 49. find the value of x