✔ 最佳答案
1. The LCM of 4 and 8 is 8, so multiply all terms by 8 we get
2x - (x + 1) = 16
2x - x - 1 = 16
x = 16 + 1 = 17.
2. The LCM of 7 and 3 is 21, so multiply all terms by 21 we get
3k + 84 = 7(2k + 1)
3k + 84 = 14k + 7
84 - 7 = 14k - 3k
77 = 11k
k = 77/11 =7.
3.Let length of side of square = x
When increasing by 8m, 2 of sides becomes ( x + 8) and ( x + 8).
When decreasing by 2m, 2 of the sides becomes (x - 2) and (x - 2).
So perimeter of new rectangle = 2(x + 8) + 2(x - 2) which equals to 40m,
that means 2(x + 8) + 2(x - 2) = 40
(x + 8) + (x - 2) = 20
2x + 6 = 20
x = (20 - 6)/2 = 14/2 = 7m.
4.
Let no. of 10 cents coins = x
so no. of $1 coins = x + 4
no. of 20 cents coins = (x + 4) + 6 = x + 10
since total no. of coins = 80
that means x + (x + 4) + (x + 10) = 80
3x + 14 = 80
x = (80 - 14)/3 = 22
22 10 cents coins = $2.20
26 $1 coins = $26.00
32 20 cents coins = $6.40
so total value = $34.60
