Question

a/b = 2/5
calculati 7a-2b/4a+3b

Answer 1

a / b = 2 / 5

a / 2 = b / 5 = K

a / 2 = K => a = 2 K

b / 5 = K => b = 5 K

⇒ ( 7 x 2 K - 2 x 5 K ) / ( 4 x 2 K + 3 x 5 K )

⇒ ( 14 K - 10 K ) / ( 8 K + 15 K )

⇒ 4 K / 23 K

⇒ 4 / 23

Answer 2

a / b = 2 / 5 ⇒ 5 a = 2 b ⇒ b = 5 a / 2

( 7 a - 2 b ) / ( 4 a + 3 b ) = ( 7 a - 2 × 5 a / 2) : ( 4 a + 3 × 5 a / 2) =

= 2 a : ( 8 a + 15 a ) / 2 =

= 2 a × 2 / 23 a =

= 4 / 23