5x+11y chia hết cho 7

=>5x+11y-21y chia hết cho 7

=>5x-10y chia hết cho 7

=>5(x-2y) chia hết cho 7

(5;7)=1=>x-2y chia hết cho 7

=>đpcm

b,5x+18y chia hết cho 13

=>8(5x+18y) chia hết cho 13

=>40x+144y chia hết cho 13

=>40x+144y-169y chia hết cho 13

=>40x-25y chia hết cho 13

=>5(8x-5y) chia hết cho 13

(5;13)=1=>8x-5y chia hết cho 13

=>đpcm

Maths exercises/He can do/he is good/at Maths./well because

He can do Maths exercises well because he is good at Maths

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Tell him (bring ) to bring his bike inside .If he (leave )leaves it there ,some one (steal) will steal it.

Sắp sếp:

is/in/It/sunny/hot/summer./and/usually //

=>> It is usually hot and sunny in summer.

Use the Past form of the verbs:

1. The waitress (tell) ....told.... us to come back in two hours.

Complete the sentences using the past simple form of the verbs.

1. They (buy).....bought..... that house last year.

2. She (not go).....didn't go...... to school yesterday.

3. That boy (have).....had..... some eggs last night.

như tek ko hay, xét tek náy cho độc

fable : ngụ ngôn

Bổ ích : useful