Problem: a new home buyer pays 4 % annual interest on her first mortgage and 9 % annual interest on her second mortgage . if she borrowed a total of $ 325,000 , 80 % of which was in the first mortgage , what is her approximate monthly interest payment ?
Rationale: "0.04 x + 0.09 y = 325000 [ 1 ] 0.04 x = 0.80 * 325000 = 260000 [ 2 ] 260000 + 0.09 y = 325000 - - > 0.09 y = 65000 [ 3 ] 260000 / 12 = 21666.67 [ 4 ] 65000 / 12 = 5416.667 [ 5 ] adding [ 4,5 ] we get : 27083.33 [ 6 ] dividing [ 6 ] / 2 to get an average we get 1.354 , ans a"
annotated_formula: subtract(9, multiply(4, const_2))