Пошаговое объяснение:
13х+12х+15=240
13х+12х=240-15
25х=225
х=9
(14х-2х):17=312
12х=312*17
12х=5304
х=442
Делители чисел 9 - 9, 3, 1
14 - 14, 7, 2, 1
32 - 32,16, 8, 4, 2, 1
37 - 37, 1
45 - 45, 15, 9, 5, 3, 1
75 - 75, 25, 15, 5, 3, 1
Кратные чисел 8 - 8, 16, 24, 32
11 - 11, 22, 33, 44
15 - 15, 30, 45, 60
25 - 25, 50, 75, 100
40 - 40, 80, 120, 160
100 - 100, 200, 300, 400
Делители чисел 9 - 9, 3, 1
14 - 14, 7, 2, 1
32 - 32,16, 8, 4, 2, 1
37 - 37, 1
45 - 45, 15, 9, 5, 3, 1
75 - 75, 25, 15, 5, 3, 1
Кратные чисел 8 - 8, 16, 24, 32
11 - 11, 22, 33, 44
15 - 15, 30, 45, 60
25 - 25, 50, 75, 100
40 - 40, 80, 120, 160
100 - 100, 200, 300, 400
а) 25x + 15 = 240
25x = 240 - 15
25x = 225
x = 225 : 25
x = 9
b) 12x : 17 = 312
12x = 312 * 17
12x = 5304
x = 5304 : 12
x = 442