Ответ:

1)90*12=1080

x-1080=423

x=1080+423

x=1503

2)900:15=60

k:60=40

k=60*40

k=2400

1) x-90×12 = 423

x-1080 = 423

x=423+1080

x=1503

2) k÷(900÷15) = 40

k÷60 = 40

k=40×60

k=2400