Question

1. 402 + [1002 : 3 - (100+a) x 2] : 14 = 408


2. 40+ 90:[9+48:(a+6] = 46


3. [(38 x a + 120 : 25 x 54] - 980 = 100


4. 7777- (77:7 + a -7777 : 7 + 777) x 7 = 777


5.[90 x (a:16-64 ) x 60 - 3980] :4 =2805

Answer 1

1.
402 + [1002 : 3 - (100+a) x 2] : 14 = 408
[334 - (100+a) x 2] : 14 = 408 - 402
[334 - (100+a) x 2] : 14 = 6
334 - (100+a) x 2 = 6×14
334 - (100+a) x 2 =84
(100+a) x 2 =334-84
(100+a) x 2 =250
100+a=250:2
100+a=125
a=125-100
a=25

2.
40+ 90:[9+48:(a+6)] = 46
90:[9+48:(a+6)] = 46 - 40
90:[9+48:(a+6)] = 6
9+48:(a+6)=90:6
9+48:(a+6)=15
48:(a+6)=15-9
48:(a+6)=6
a+6=48:6
a+6=8
a=8-6
a=2

3.
[(38 x a + 120 : 25 x 54] - 980 = 100
[(38 x a + 3 000 x 54]= 100 + 980
[(38×a+162 000]=1 080
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4.
7 777- (77:7 + a -7 777 : 7 + 777) x 7 = 777
(11 + a -1 111 + 777) x 7 = 7 777 - 777
(11 + a -1 111 + 777) x 7 = 7 000
11 + a -1 111 + 777=7 000:7
11 + a -1 111 + 777=1 000
11 + a -1 111 =1 000-777
11 + a -1 111 =223
11 + a=223+1 111
11 + a=1 334
a=1 334 - 11
a = 1 323

5.
[90 x (a:16-64 ) x 60 - 3980] :4 =2805
90 x (a:16-64 ) x 60 - 3980=2805×4
90 x (a:16-64 ) x 60 - 3980=11 220
90 x (a:16-64 ) x 60 =11 220+3 980
90 x (a:16-64 ) x 60 =15 200
90 x (a:16-64 ) =15 200:60
90 x (a:16-64 ) = 253,33 (aprox)
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