\(-2+\left(-2\right)=-4\)

\(-2345+\left(-6753\right)=-9098\)

a)  15 mảnh lưới chú Đức mua có độ dài là :

                   1,4 x 15 = 21 (m)

Mà chỉ cần 20m lưới để che hoa nên số lưới chú mua đủ dùng.

b) Ta có : 21 : 0,8 = 26 (dư 0,25)

Vậy nếu chú Đức cắt số lưới đã mua thành các mảnh lưới dài 0,8m thì được 26 mảnh lưới như thế và dư 0,25m lưới nữa

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tìm chữ I

Tuổi mẹ là :

(50 + 30) : 2 = 40 (tuổi)

Tuổi con là :

50 - 40 = 10 (tuổi)

Tuổi bố là :

40 + 5 = 45 (tuổi)

mẹ:40

con:10

bố:45