a sum of money at simple interest amounts to $ 700 in 3 years and to $ 764 in 4 years . the sum is :
"a $ 508 s . i . for 1 year = $ ( 764 - 700 ) = $ 64 . s . i . for 3 years = $ ( 64 x 3 ) = $ 192 . principal = $ ( 700 - 192 ) = $ 508 ."
subtract(700, divide(multiply(subtract(764, 700), 3), 4))