if ( c - a ) / ( c - b ) = 1 , then ( 5 b - 4 a ) / ( c - a ) =
"let ' s say c = 3 , b = 1 , a = 1 so that our 1 st expression holds true . now , ibsert those numbers in the second expression and we ' ll get 0.5 answer a ( hopefully ) ) )"
multiply(subtract(5, 4), 4)