Goi so chi tiet may to 1 lam duoc trong thang dau la x ( dk:x>0 )
Khi do so chi tiet may to 2 lam duoc trong thang dau la 800-x
Thang thu 2, to 1 lam duoc 15/100x = 3/20x
Thang thu 2, to 2 lam duoc 20/100 ( 800-x ) = 1/5 (800-x)
Ca hai to lam duoc :945-800 = 145 (chi tiet may )
Theo de bai ta co pt :
2/30x + 1/5 (800-x) = 145
⇔ 2/30x + 160-1/5x = 145
⇔ 3x + 3200 - 4x = 2900
⇔ -x + 3200 = 2900
⇔-x = -300
⇔ x = 300 (TM)
Vay so chi tiet may to 1 lam duoc trong thang dau la 300 chi tiet may
So chi tiet may to 2 lam duoc trong thang dau la 800-300 = 500 chi tiet may