Упр.143 Часть 1 ГДЗ Дорофеев Петерсон 5 класс (Математика)

1) 55 — 8х = 7; 5) (60а — 30) : 5 = 18;
2) 27 : у + 29 = 38; 6) 92 + 56 : (14 — b) = 100;
3) (t — 25) : 20 = 9; 7) (с : 9) · 15 — 47 = 28;
4) 6 · (18 — k) = 54; 8) (410 — d) : 7 + 70 = 120.

1) $$55 — 8x = 7$$

$$ 8x = 55 — 7 \\ 8x = 48 \\ x = 48 : 8 \\ x = 6 $$

2) $$27 : y + 29 = 38$$

$$ 27 : y = 38 — 29 \\ 27 : y = 9 \\ y = 27 : 9 \\ y = 3 $$

3) $$(t — 25) : 20 = 9$$

$$ t — 25 = 9 \cdot 20 \\ t — 25 = 180 \\ t = 180 + 25 \\ t = 205 $$

4) $$6 \cdot (18 — k) = 54$$

$$ 18 — k = 54 : 6 \\ 18 — k = 9 \\ k = 18 — 9 \\ k = 9 $$

5) $$(60a — 30) : 5 = 18$$

$$ 60a — 30 = 18 \cdot 5 \\ 60a — 30 = 90 \\ 60a = 90 + 30 \\ 60a = 120 \\ a = 120 : 60 \\ a = 2 $$

6) $$92 + 56 : (14 — b) = 100$$

$$ 56 : (14 — b) = 100 — 92 \\ 56 : (14 — b) = 8 \\ 14 — b = 56 : 8 \\ 14 — b = 7 \\ b = 14 — 7 \\ b = 7 $$

7) $$(c : 9) \cdot 15 — 47 = 28$$

$$ (c : 9) \cdot 15 = 28 + 47 \\ (c : 9) \cdot 15 = 75 \\ c : 9 = 75 : 15 \\ c : 9 = 5 \\ c = 5 \cdot 9 \\ c = 45 $$

8) $$(410 — d) : 7 + 70 = 120$$

$$ (410 — d) : 7 = 120 — 70 \\ (410 — d) : 7 = 50 \\ 410 — d = 50 \cdot 7 \\ 410 — d = 350 \\ d = 410 — 350 \\ d = 60 $$

Ответ

1) $$x = 6$$; 2) $$y = 3$$; 3) $$t = 205$$; 4) $$k = 9$$; 5) $$a = 2$$; 6) $$b = 7$$; 7) $$c = 45$$; 8) $$d = 60$$.