538=5.100+3.10+8.1

3^x + 3^{x + 1}=36

3^x . 1 + 3^x . 3 =36

3^x . (1+3)=36

3^x . 4 = 36

3^x = 36 : 4

3^x = 9

3³ = 9

=> x = 3

vậy x = 3

5¹²:5⁸=5^12-8=5⁴

n=1

n=0

Tổng hiệu sau là số tự nhiên hay hợp số

lộn đề

thông cảm

120+5(x-4)=200

5(x-4)=200-150

5(x-4)=50

(x-4)=50:5

(x-4)=10

x =10+4

x =14

vậy: x =14

book books ; school schools

door doors classroom classrooms

board boards ; ruler rulers

clock clocks eraser erasers

bag bag ; house houses

pencil pencils ; street

pen pens

what do they do ? they are engineers

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