Ta có:
a) (285 - x - 0,15 ) : 0,25 = 15 : 0,25
(285 - x - 0,15 ) = 15
284,85 - x = 15
x = 284,85 - 15
x = 269,85
a)
( 285 - x - 0,15 ) : 0,25 = 15 : 0,25
(285 - x - 0,15) : 0,25 = 60
(285 - x - 0,15 ) = 60 x 0 , 25 = 15
=> 285 - x - 0,15 = 15
=> 285 -x = 15 + 0,15
=>285 - x = 15,15
=> x = 285 - 15,15
=> x = 269,85
b)
520 + 30 = \(\frac{x+175}{5}\)+30
=> \(\frac{x+175}{5}\)= 520
=> x+175 = 520 x 5
=> x+175 = 2600
=> x= 2600 - 175
=> x = 2425