Bài 2 nhé cần gấp lắm

Đáp án:

a) 315 - (215 - x) = 215
<=> 215 - x = 100
<=> x = 215 - 100 = 115
b) 2 . (3x - 8) = 64 : 8
<=> 6x - 16 = 8
<=> 6x = 8 + 16 = 24
<=> x = 4
c) (3x - 8) . 7 = 2 . 14
<=> 21x - 56 = 28
<=> 21x = 84
<=> x = 84 : 21 = 4
d) [(x + 32) - 17] . 2 = 42
<=> (x + 15) . 2 = 42
<=> x + 15 = 42 : 2 = 21
<=> x = 21 -15 = 6
e) [61 + (53 - x)] . 17 = 1785
<=> 114 - x = 1785 : 17 = 105
<=> x = 114 - 105 = 9
f) 88 - 3(7 + x) = 64
<=> 3 (7 + x) = 88 - 64 = 24
<=> 7 + x = 24 : 3 = 8
<=> x = 8 - 7 = 1.