Answer: how many friends did she have ?
Step-by-step explanation:
A. 3x + y = 13 → 15x + 5y = 65
x - 5y = 15 → x - 5y = 15
16x = 80
16 16
x = 5
x - 5y = 15
5 - 5y = 15
- 5 - 5
-5y = 10
-5 -5
y = -2
(x, y) = (5, -2)
b. 6x - y = 14
2x + y = 12
8x = 26
8 8
x = 3¹/₄
6x - y = 14
6(3¹/₄) - y = 14
19¹/₂ - y = 14
- 19¹/₂ - 19¹/₂
-y = -5¹/₂
-1 -1
y = 5¹/₂
(x, y) = (3¹/₄, 5¹/₂)
c. 3x - 4y = 22 → 15x - 20y = 110
2x + 5y = 7 → 8x + 20y = 28
23x = 138
23 23
x = 6
3x - 4y = 22
3(6) - 4y = 22
18 - 4y = 22
- 18 - 18
-4y = 4
-4 -4
y = -1
(x, y) = (6, -1)
Answer:
n ≤ 4
Step-by-step explanation:
"The difference between a number and seven is less than or equal to -3" translates into n - 7 ≤ -3. To solve, isolate the variable n.
n - 7 ≤ -3
n ≤ -3 + 7
n ≤ 4
