4.2 x 4.2 - 1.9 x 1.9 / 2.3 x 6.1 is equal to :
"given expression = ( a 2 - b 2 ) / ( a + b ) ( a - b ) = ( a 2 - b 2 ) / ( a 2 - b 2 ) = 1 . answer is b ."
divide(subtract(multiply(4.2, 4.2), multiply(1.9, 1.9)), 2.3)