1. a) 2348 : 15 = 156 rest 8; b) 125673 : 32 = 3927 rest 9; c) 987 : 123 = 8 rest 3.
2. a : 100 = 99 rest 98 ⇒ a = 100 · 99 + 98 = 9900 + 98 = 9998.
3. a + b = 72
a : b = 2 rest 15 ⇒ a = 2b + 15
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a, b = ?
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a + b = 72
2b + 15 + b = 72
3b + 15 = 72 /-15
3b = 57 /:3
b = 19.
a = 2b + 15
a = 38 + 15 = 53.
/robertinni
