Question

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Answer 1

n = ecuatii ; n ∈ N*

30 % din n a rezolvat in prima zi

30 / 100 = 3 / 10 din n → prima zi

n - 3 n / 10 = 10 n / 10 - 3 n / 10 = 7 n / 10 → restul ecuatiilor

40 % din 7 n / 10 ⇒ 40 / 100 = 2 / 5 × 7 n / 10 = 14 n / 50

7 n / 10 - 14 n / 50 = 42 ecuatii

35 n - 14 n = 50 × 42

21 n = 50 × 42

n = 50 × 42 / 21 = 50 × 2 = 100 ecuatii

a) Raspuns: n = 100 ecuatii au primit

b) 3 / 10 din 100 ⇒ 100 : 10 × 3 = 10 × 3 = 30 ecuatii a rezolvat in prima zi

c) 100 - 30 = 70 ecuatii → restul ecuatiilor

40 % din 70 ⇒ 2 / 5 din 70 ⇒ 70 : 5 × 2 = 14 × 2 = 28 ecuatii a rezolvat a doua zi

Verific: 30 + 28 + 42 = 100 ecuatii

Answer 2

prima zi=nx(30/100)=3n/10 ecuatii rezolvate, n-3n/10=7n/10 ecuatii ramase

a doua zi=(7n/10)x(40/100)=(7n/10)x(2/5)=14n/50=7n/25 ecuatii rezolvate

n=3n/10+7n/25+42, numitor comun 50

50n=15n+14n+2100

21n=2100, n=2100/21=100 ecuatii

b) 3n/10=300/10=30 ecuatii rezolvate in prima zi

c) 7n/25=700/25= 28 ecuatii rezolvate a doua zi